For words that have only 3 letters, there is no 4th letter. For instance with the word “increase”, there won't be any much more letters Later on and thus needs to be the word "insert". The word “addict” is within the BIP39 wordlist but you might have employed “addi” for https://bookmarkerz.com/story18734288/the-ultimate-guide-to-bip39-seed-phrase-github