I think I started to remember smth. I could generate an electrum seed fraze. Then when restoring selected Bip39 "to check compatibility", ignoring "bip39 checksum failed". Electrum allowes that. (I didn't know it altered adresses). Then probably changed smth in derivation path.
The question is how do I check all derivation paths, knowing seed fraze and 2 adresses.
Electrum doesn't generate BIP39 seeds, so you are just contradicting your statements. But the checksum failed warning is for the BIP39 seeds that are generated in BIP39 compatible wallet and you can import that on electrum and checksum is to verify the correctness of the entered seeds, so if you get a warning then it means entered seeds were incorrect.
You can ignore the warning and proceed when you are sure the seeds are right but it just generate the address as per the derviation path that you chose.
I recommend you to move this thread to
Electrum section.