I'm sure that chant may have some little quirks of its own.
Our choirmaster uses the guide to pronunciation in the front of the "Chants of the Church" book - Spence, Charles E., ed., Chants of the Church: Selected Gregorian Chants. (Toledo, Ohio: Gregorian Institute of America, 1953.) It's a very dense 3 pages that explains it all.
The great thing about this book is that it includes (in red) an interlinear translation under the Latin. It is a strictly literal word-for-word translation, which means the English doesn't make sense at first glance, but it sure helps with Latin comprehension! I found a copy of my own on line dirt cheap (it's of interest to nobody but choir singers who do chant).
I learned “classical Latin” in a classical high school curriculum which changed over (got dumb) in my third year.
I “served” Latin saying “Church Latin” with an old Pastor who was born before Vatican I, I think.
So, pardon me if I get mixed up. There are differences. Classical uses “hard C’s” all the time whereas Church uses the “CH” sound (as in caelum).
What we need is to have the Pope give us the go ahead so we can exercise those Latin muscles again!