When creating a wallet, click on Options and choose "Extend this seed with custom words".
Type the custom words you want, and you have to back up (write down) both wallet seed words and your custom words.
Yes! lso something I used recommend to people from where I come from (there is almost no interest now). My native language isn't spoken by many, does not have a full formal dictionary, and does not have a very ambiguous latinised spelling. I think most local dialects are similar, and that makes it a natural defence against major language brute force.
If we were to compare the differences between these two wallets, it really comes down to radically different approaches to open-source and transparency. Electrum operates under standard, OSI-approved open-source licenses. Anyone can fork, inspect, modify, host, or re-distribute the code without restriction. A true Open Source. Because it is used as the codebase for countless wallet integrations, and thousands of independent developers regularly fork, test, compile, and stress-test the code.
Coldcard, on the other hand, has the "source available" facade. They transitioned their firmware to a proprietary license with a commons clause. This prevented independent developers from using their code, commercially or non-commercially. Because of this, developers outside of Coinkite had little incentive to actually build with, maintain, or deeply test the firmware.
This is exactly what brought them to their doom, in my opinion. The sheer arrogance and poor licensing decisions of their founder and CEO, Rodolfo Novak (aka
nvK).
Then my suspicions, laid out in non-technical terms, are well-founded.
Battle-tested is what I have said before as my preference. A base source that so many people used (when I started out, using alt wallets, I even thought this was simply default, understanding later that almost everything I used simply derived from Electrum). Without needing to know much, just basic observation over the 10+ years I've used Electrum tells me I'm in safe(r) hands than switching to something that, even when open source, is at the bottom limits of the definition.