For words that have only 3 letters, there isn't any 4th letter. For example with the word “insert”, there aren't any more letters Later on and thus needs to be the word "increase". The word “addict” is during the BIP39 wordlist however you might have employed “addi” for “addict”. If https://social4geek.com/story4387237/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news