Bip39 Checksum. While there are actually BIP39 wordlists in languages other than English, it truly is strongly not recommended to make use of non-English words for wallet backups. It'd make restoring the wallet difficult or impossible. BIP39 specifies a list of 2048 words from which the mnemonic phrase is decided https://zbookmarkhub.com/story19187134/bip39-word-list-https-linktr-ee-bip39-getting-my-bip39-wallets-to-work