The 22.0 version I have is fully synced and ready. It's just that it doesn't have a 'debug window', 'console'
Click Window > Console (at list this is how it shows in my version).
Or press CTRL-T.
Keep your paper wallet backup.
If your wallet is from early 2017, you probably also own some Forkcoins. Don't do anything with them before you move all Bitcoin to a new address.
When you "import" a private key, the wallet continues to hold and use the private key. You should destroy all copies of the private key after it is imported because the bitcoins haven't moved and the private key still gives access them.
Don't destroy your paper wallet, just make sure nobody can get to it!
If it's a large value, you may want to find a different solution than keeping everything on a computer connected to the internet.