Every time a checksum is invalid, warn the person which the phrase is just not a thing created by your app, and question if they would want to use it in any case. This way, your application only needs to maintain the wordlists for your supported languages, but you can https://mnobookmarks.com/story18762023/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-seed-phrase-mnemonics-generator