For words that only have 3 letters, there isn't any 4th letter. For instance with the word “insert”, there are no far more letters afterwards and thus have to be the word "increase". The word “addict” is during the BIP39 wordlist but you might have employed “addi” for “addict”. The https://social-lyft.com/story9373765/examine-this-report-on-bip39-passphrase