No, the correct word would be "the standard" since it's the most implemented mnemonic seed for HD wallets.

"Backward compatible" is: If the new version of a software still supports something from its old version.
For example: Electrum's old seed is different from the new ones but it can still be imported to the latest version.
(take note that none of those seed phrases are BIP39)

It's not enough and probably dangerous due to the subpar quality specially that PWM generic charger controller which doesn't have proper protections.

Here's what I can say about each parts:

Set: The kit doesn't even come with a power inverter so you'll have to make use of the battery and/or charger controller's 12v output.

Solar panel: As others have mentioned, the power output is just too low.
In comparison, my 320W (160W+160W parallel) panels can only produce about 180W~200W at noon and 60W~120W of power in early morning and afternoon until 3 or 4PM. (sunny weather)
Not to mention, it usually drops extremely low if it's too cloudy, you'll likely get 1W on cloudy weather.
BTW, I installed them two years ago for a "test" and still working today (BOSCA Brand).

Battery: You can only safely drain that kind of "SLA battery" down to 50% or it'll end up broken within months.
It's based from self-experience since I've once busted a 100Ah SLA battery in just 4months by directly connecting 2pc 12v LED lights that are running about 18hrs/day
(even until the voltage drops below 11.6v)

Your very small battery can only provide you 3.5Ah x 12v which is about 42Wh of stored power (more if you'll push it to 30%).
So after "daylight", you'll only have 42Wh before your battery drain down to critical levels.

Overall, If you want to solar power your RPi node, buy at least 120W solar panel, MPPT solar charger controller and bigger LiFePO4 battery enough to run the load when there's no sunlight.
Because it's not just the output of the panels but also the capacity of the battery and the panel's capability to top it up while being used/bad weather.

What is the name of the lightning wallet that you've used?
Because based from the information provided, it looks like some feature of a custodial lightning wallet.

If we're talking about the standard lightning implementation,
force-closing it with 5000 sat local balance will result with 5000sat on-chain fund minus the fee, you'll loose the remote balance since it's the other party's funds.
Broadcasting an old state when the local balance is 10000sat is dangerous since it could lead to a penalty of losing all of your balance.

...And this is where some "signing issue" came from.
This setup can generate address without any issue, good enough for watching-only wallets.

Problem is, hardware wallets need to know the derivation path to be able to sign the transactions linked to the provided xpub.
This is why MultiSig descriptors with hardware wallets starts from "m" and not directly from xpub.
Ref: github.com/bitcoin/bitcoin/blob/master/doc/descriptors.md#bip32-derived-keys-and-chains

BIP49 is for Nested-SegWit Purpose field but most wallets aren't strict on the derivation path used.
Since it's still set 'on', then the path must have been different from the single-sig Nested-SegWit default m/49'/0'/0' and higher account index which Sparrow wont accept for MultiSig. (test it)
(or maybe it was setup in older versions when the feature isn't implemented yet)

Yes that's true, the release version which isn't updated since 2021 is using its own backup scheme.
But the development version has recently updated with BIP39 support just 4 months ago, the developer doesn't have an ETA on the release date though.

Reference: https://github.com/goatpig/BitcoinArmory/pull/692

Yes, I checked "commands.py" and nothing in it outputs the 'fee rate' or 'transaction size'.
Link: https://github.com/spesmilo/electrum/blob/master/electrum/commands.py

deserialize also do not return with the transaction's fee rate, just the exact data in the raw transaction.

That's great news for OP.
However, I can't seem to find an option limit the search space of each specific position; the feature seem to affect all of the MissingChar symbol.

But since it's not torn, the rest are still barely visible, yes?

If so, you may be able to lower the characters to bruteforce by guessing the possible washed-out characters.
Depending on the condition, you may be able to minimize it to a doable difficulty.

For example: a small circular washed-out character could be an 'a', 'o' or 'c'.
Then when bruteforcing the private key, input those as the possible characters of that specific place.
The issue is, I don't know any private key bruteforcing tool that does that so you might have to search for one yourself of find someone to code it for you.

If it's totally unrecognizable, then there's no chance to bruteforce it.

I have no means to test this but you may be able to sign by creating a new MultiSig wallet with the correct derivation paths to the provided extended public keys.

I checked and that safety check can indeed be disabled.
Maybe you have the safety setting "Validate Derivations" disabled that enabled you to use the single-sig derivation paths to MultiSig.

Perhaps.
If those Nested SegWit extended public keys are derived from your master private key with m/49'/0'/0' path,
But used it in a MultiSig setup and provided the standard path of m/48'/0'/0'/1' (BIP48 - Nested SegWit), then your hardware wallet will derive a different xpub key than what you've provided.

What does the descriptor looks like? You can edit the extended public keys for privacy reasons.
BTW, in Sparrow, you can't use the standard derivation path of BIP49 in a MultiSig setup by design.

You might want to snip-out the secret part of the contents of your dump.txt file since the private key and WIF private key are in there.
Even if it's empty, it's not a good idea to share your old wallet's keys and addresses.

For some reason, the WIF private key isn't formatted correctly for Litecoin;
perhaps there's something wrong with your --otherversion arg or it doesn't support LTC.

The workaround is to use "hexsec" which is your ECDSA Private key and encode it into WIF using encoding tools.
For example, the "Wallet Details" tab of liteaddress.org can convert it into WIF (but only use it offline).
Source Code: https://github.com/litecoin-project/liteaddress.org

I completely missed the MultiSig part of the question.

Yes, there's an option in Android Electrum to import master public keys as cosigners.
Just follow the correct options when restoring a wallet, the options are self-explanatory: "Multi-signature wallet->Select the number of Cosigners/Signatures->Use a master key"
but like in single-sig, the extended public keys should be converted for Electrum to be able to derive the correct address type, otherwise it'll be restored as P2SH-MultiSig.

With that, if your addresses are P2SH-MultiSig, import them as is.
If not, and the addresses starts with "bc1q", you'll have to convert them into "Zpub".

Orbot seems to work without issues in my test.
Check out these screenshots (connected to a randomly picked onion server):


Things that you might have missed: have you enabled Orbit's "VPN" during its setup and added Electrum to the Tor-Enabled Apps?
It's also have to establish connection first by clicking the Electrum icon (screenshot 2).

In Electrum, your option is to restore separate wallet files with each xPubs.
You'll also might need to convert them first into zPub/yPub depending on the script type that you want to restore, otherwise, it'll be legacy.
Electrum (Desktop) has a built-in tool for that, use the command: convert_xkey

Technically, it's not an issue since each of your MultiSig Addresses are derived from each cosigner's individual child keys.
The derivation path is just a way to tell the client a way to derive child keys.

Signing wont be an issue either as long as the client know how to derive those child keys from the master key.

As for Sparrow, it's using "Descriptors" to take note of the derivation path for each cosigner master keys.

Electrum never adapted nor invented BIP39, so I doubt that it's a BIP39 seed phrase.
Depending on the actual date, it could be an actual old electrum seed format or the one described by pooya which was implemented hours/day after the first release.
Even though the former can be imported to the latest version, the keys will be different than what he can restore in the old versions due to the mentioned bug.

But seeing OP isn't interested in his thread, there's a fat chance that this is just one of those "usual" topics about recovering old bitcoins.

The message is hard-coded to the server.
Here's where the code is: github.com/chris-belcher/electrum-personal-server/blob/master/electrumpersonalserver/server/common.py#L84-L86

If it's actually from Electrum's old release (disregarding the date), then restoring the correct keys and addresses will be hard.
That's because clients before version 0.31 have different key derivation than the later versions due to a major bug.

One trick that might work is to restore it in version 0.3 and create a lot of receiving addresses (via "New address").
Then find the associated "electrum.dat" file (wallet file) in Electrum's old data directory and open it as text, the private keys should be in plain text.
Those can now be imported to the latest version or other clients.

ETFbitcoin managed to install it and provided a guide, link: https://bitcointalk.org/index.php?topic=5379817.msg58942538#msg58942538

You have two options: fix that issue or manually broadcast the transaction using other clients or push txn service.
If you only need to send this one time, I'd recommend the latter.

For the former, I've seen it in many topics here but there's no universal solution to it.
As per usual, check or share your logs (Armorylog.txt and dbLog.txt) to see the possible cause of the issue.

For the latter, you can get the signed raw transaction (HEX) and broadcast it elsewhere.
Here's how to do it:

• Click "Send Bitcoins", fill up the recipient and amount as usual.
• Tick "Create Unsigned" Below before clicking "Continue".
• The 'Review Offline Transaction' window show, click "Copy to Clipboard" and then "Continue".
• In the next window, paste that unsigned raw transaction, then click "Sign" (check if everything's correct and type your password).
• Next, click "Click here for more information about this transaction".
• Then in the 'Transaction info' window, click "Copy Raw Tx (Hex)".
• Go to your favorite broadcast service like blockstream.info/tx/push or blockchair.com/broadcast?chain=bitcoin; and paste that signed raw transaction to send it to the network.
  
  

You can also broadcast it using your Bitcoin Core by using sendrawtransaction command.

During that time, are you using the GUI or bitcoind?
Because the latter wont use the GUI's setting and will use the default data directory's config file by default.

Anyways, since you've included those in your config, try adding  --rpcuser=bitcoin and --rpcpassword=yourpassword in your command
since there seem to be a problem in the cookie file which should've been created automatically.

In your example, you've indicated the absolute path but it has a whitespace so command prompt took "C:\Program" (before the whitespace) as command.
In that case, enclose the absolute path with quotation marks;
For example, the correct command should be: "C:\Program Files\Bitcoin\daemon\bitcoin-cli" stop

But I recommend you to always use 'change directory' so that you can use bitcoin-cli without specifying the absolute path in every command.

If you've set the data directory in the Welcome Screen, then the 'bitcoin' folder in the default directory wont be created and wont be used.
You should instead create the bitcoin.conf file inside your custom data directory.

Create a "bitcoin.conf" file inside your custom data directory and write server=1 on it.
Restart Bitcoin Core, then try using bitcoin-cli commands again.

Take note that it should be "bitcoin.conf" not "bitcoin.conf.txt" so enable Window Explorer's "View->File name extensions" to see its actual extension.