A "liturgist" is a lay person appointed in some parishes to "run the show". They are the ones responsible for a lot of nonsense like giant puppets, clown masses, goofy pop music, etc. They are almost always screaming liberals, because in an orthodox/traditional parish there isn't any "show" and no need to "run" it. The priest simply follows the rubrics ("Say the black, do the red.")
Because they are liberals, they loathe things like Confession and Adoration and Gregorian Chant. They want the Church to be white bread mainline liberal Protestant. They would be more comfortable with the Episcopalians, but they just won't leave.
Thank you.