I took the index on the words, converted the number to binary, included three zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to transform it to binary, additional a few zeros to your 8 digits on the binary and obtained 00000010011 which interprets to 19 in https://bookmarkingquest.com/story19081298/the-basic-principles-of-bip39-passphrase-generator