Also remember that you should also store the list alongside the mnemonic otherwise you won't be able to recover your keys.
This is not necessary with Electrum. You can import a seed phrase created with an unknown word list and it will still be able to both verify the version bits are correct and generate the corresponding wallet. This is because the checksum is not dependent on decoding the final word to its relevant bits as it is with BIP39 (where you
do need to know the word list), but because Electrum seed phrases are simply normalized and hashed to obtain the version bits.