Where does the Catholic Church claim this? Can you point me to some official document?
Nobody really has any idea what is really practiced by the adherents unless you are one.
I cannot determine to whom you are referring with the term 'adherents': do you mean Catholics, or those practicing Santeria?
When the Church was or is communicating with its subjects in Latin, none of them know what is really written or said. Thus you need your mediators to interpret.
There is some truth to that, but I don't see how that pertains to your original claim.
The whole Mass thing is purely mystical and has no authority from the scriptures.
Wow. Let me recommend two books: The Mass of the Early Christians by Mike Aquilina, and The Lamb's Supper: The Mass as Heaven on Earth by Scott Hahn. Both should clear up your misconception of the mass.
There is a whole section of Catholic belief devoted entirely to mysticism, even today, and encouraged.
And, what's wrong with mysticism?
-A8
What indeed