I beg to differ with you and Hahn. There is not "as much evidence for the Matthean Priority as the Markan." If your idea of evidence is Eusebius' quote about Papias, then that isn't very good "evidence." Papias is 100 years after Christ and Eusebius, who is telling us what he heard/read is another century and more after Papias. Nowhere does the Church declare either man's statements as Spirit-inspired. When Origen (AD 210?) says, "The first is written according to Matthew" we don't know whether he means first to be written or first as it is found in the collection. The fact that no one quotes Matthew in his "original" Hebrew is also telling. Jerome's translation is based on the Greek Matthew. Hahn's statement that the Church doesn't demand that we have to believe in Marcan priority is a poor defense of Matthean priority IMHO.
Sometimes the easiest solution is the right one. But ultimately what matters is the inspired Word of God, not who wrote it or when.
Also, how does the translation of the second person singular pronoun "you" relate to the "apalling (sic) state of the Liturgy"? How else would you translate it into contemporary English? Remember, Jerome's Vulgate was intended to make the Word accessible so he used the everyday Latin. That's the task of contemporary translators as well. I'm sure people complained about his "modern" translation as well.