I took the index of your words, transformed the amount to binary, added a few zeros, calculated the sha256 digest, took the main Section of the hexadecimal to convert it to binary, included 3 zeros towards the eight digits with the binary and acquired 00000010011 which translates to 19 in https://digibookmarks.com/story19567305/the-basic-principles-of-bip39-passphrase-generator