Oh, I just noticed this because I translated John's exorcism in Volume 6. His words are from the Gallican Rite which I found referenced in Lucifer: The Devil in the Middle Ages by Jeffrey Burton Russell (pg 126) written in 1986. There's a preview on Google books. John likes to pick out pieces from this.

Again, thanks for translating this! You're such an inspiration! I read this all the time.