I don't know about catholic priests and Latin - my son was married in a foreign country, and his local priest in UK had to write a letter in Latin to the priest who was to do the ceremony. It was an open letter, which my son showed me. It was only a couple of sentences, but it was full of mistakes in the Latin. It may have something to do with the Vatican Cardinal who is ( or used to be) in charge of the Latin for official Vatican publications - bulls and encyclicals , and so on. He had to give certificates to student-priests to show they had sufficient Latin, but he would often give these certificates out to students who admitted that they didn't want to learn Latin but were only doing it to qualify for ordination. He did so on the grounds that he didn't want to teach Latin to anyone who didn't want to learn it, so he would say " Not interested in Latin ? here's your certificate, now go away".