Whenever a checksum is invalid, alert the user the phrase is just not something generated by your app, and question when they want to use it anyway. Using this method, your application only really should maintain the wordlists for your supported languages, but you can Get better phrases produced by https://bookmarkize.com/story19050257/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting