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 Later on and therefore have to be the word "include". The word “addict” is from the BIP39 wordlist but you would've used “addi” for “addict”. The https://bookmarkvids.com/story20899599/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-seed-phrase-mnemonics-generator