Yes, of course, we cannot with any certainty claim to the contrary anything that is not written, or for that matter with equal certainty, claim that it was. We can perhaps presume and not much more than that.
Yes, we do mention the Virgin Mary at EVERY Mass
I couldn't imagine otherwise, but wasn't sure. Thank you for educating me.
It is hard to make that claim, because he certainly could have been relating a "tradition" of whom the author was
Actually 1 Clement quotes from vatrious Gospel verses but never mentions any of the authors. It simply says "lord Jesus Christ said..."
Whatever the custom was, +Ireanaeus found it necessary to credit the authors. Others before him apparently didn't.
I am sure you are well aware that the Church Fathers often did not "cite" the Scripture chapter and verse - they merely relate "It is written...". The editors of the various books on the Church Fathers add the Scriptural locations of their citations for us who have not memorized the Bible yet!
Of course, I agree with you that the names of the writers of the Gospels are based on tradition.
Regards