For words that have only 3 letters, there isn't any 4th letter. Such as with the word “insert”, there isn't any more letters Later on and so need to be the word "include". The word “addict” is during the BIP39 wordlist however , you might have utilized “addi” for “addict”. https://bookmarkfly.com/story18842670/facts-about-bip39-seed-phrase-github-revealed