Bip39 Vs Slip39. Though there are BIP39 wordlists in languages in addition to English, it can be strongly not advised to employ non-English words for wallet backups. It would make restoring the wallet tough or difficult. BIP39 specifies a list of 2048 words from which the mnemonic phrase is decided https://tornadosocial.com/story4445662/bip39-wallets-https-linktr-ee-bip39-bip39-wallet-fundamentals-explained