I took the index in the words, converted the selection to binary, additional a few zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to transform it to binary, included three zeros to your 8 digits on the binary and obtained 00000010011 which interprets to 19 in https://bookmarkshome.com/story4552183/getting-my-bip39-words-to-numbers-to-work