3) After that I closed my browser and waited for the transaction to be confirmed.
4) I tried to log into Sudoku wallet a few hours later, but got an error: Wallet Key Not Found.
Clearnet or TOR browser?.
Fee 40sat/byte I think not a half hours to be confirmed, why you so late, waiting
4 hours to use electrum?
0.48455333 BTC lost in this address 12Czrsks5H3jtmVUqUnqZLW45xqX3Qq9SH where you have a private key. I am not sure what going on, in this case, you and sudokuwallet can access it.
I see sudoku wallet support mail is
sudokuwallet@protonmail.comYour proof at begining received email address from
gosouza@protonmail.com Q: what email address you sent wallet key?