I took the index of your words, transformed the quantity to binary, added three zeros, calculated the sha256 digest, took the 1st Section of the hexadecimal to transform it to binary, included a few zeros to the eight digits of the binary and received 00000010011 which translates to 19 in https://bookmarktiger.com/story18792378/a-secret-weapon-for-bip39-words-to-numbers