Bip39 Ian Coleman. Though there are actually BIP39 wordlists in languages aside from English, it can be strongly not advised to use non-English words for wallet backups. It might make restoring the wallet tricky or unachievable. BIP39 specifies a list of 2048 words from which the mnemonic phrase is decided https://active-bookmarks.com/story18701814/bip39-wallet-https-linktr-ee-bip39-bip39-words-secrets