For words that only have 3 letters, there isn't a 4th letter. For instance with the word “insert”, there won't be any extra letters afterwards and thus has to be the word "add". The word “addict” is inside the BIP39 wordlist however, you would have made use of “addi” for https://bookmarkstumble.com/story20531629/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-seed-phrase-mnemonics-generator