Bip39. While you will find BIP39 wordlists in languages in addition to English, it really is strongly not recommended to use non-English words for wallet backups. It would make restoring the wallet difficult or difficult. And not using a passphrase, your cash are only as secure as your seed phrase. https://cyberbookmarking.com/story18740183/ian-coleman-bip39-https-linktr-ee-bip39-5-simple-statements-about-bip39-mnemonic-explained