For words that have only three letters, there is not any 4th letter. Such as with the word “insert”, there isn't any additional letters Later on and so have to be the word "incorporate". The word “addict” is during the BIP39 wordlist however you would've applied “addi” for “addict”. Art https://dirstop.com/story23332790/little-known-facts-about-bip39-seed-phrase-list