Approximately 8 million years ago, I recorded several Gregorian chants for a community theatre production of Agnes of God. My mentor, a former nun, helped me with the Latin pronunciation. I was surprised to discover that the R is not flipped in Latin but is pronounced as it is in English. But since everyone expects to hear it flipped, vocalists sing it that way in the Ave Maria and everything else in the canon!
The recording process was delightful: a choral mic was suspended in the middle of our huge auditorium stage so it sounded like I was in a cathedral. And I was, indeed, in the cathedral of my choice.
As far as I know, all traces of these recordings have disappeared.