Keystone Bip39 Some words are shorter than 4 letters, including the word “act”. Other words are more time than four letters, which include “abstract”. You should make sure to allow recovery from mnemonic phrases which have invalid checksums (or that you do not have the wordlist) This article explains BIP39, https://www.youtube.com/channel/UCUpxfyTJ0fb78SQ55hU6OCw