What is "Textual Criticism,"? I thought I'd offer a few words about what that term means ... because, in my bitter experience, even very well-informed people often misunderstand it. You can even find the term misunderstood in otherwise respectable books.
Textual Criticism does not mean commenting on a text; going deeply into its meaning; explaining to people who don't understand it what the author was getting at; still less does it mean criticising it in the sense of explaining why it's wrong!
Textual Criticism means this: -
Pre-modern and early modern editions of an ancient text rarely give us that text as it sprang like Athene straight from the head of its author. Almost invariably, a text has been transmitted by scribal copying, during which changes will have been made. Sometimes these changes are mistakes (like leaving out a line in error); sometimes they are intentional (I can improve that; or He can't really have meant that; or I think I'll bring this verse of S Mark into line with the parallel passage in S Matthew; or This is in rather awful Greek ... I'd better correct it ...etc. ad infinitum). So you will find that no two manuscripts are entirely the same.
Textual Criticism means using very many different skills to try to get back, from the available copies, to what the author actually did write. Although ... many of us now doubt whether the 'original text' really is always (even in principle) ascertainable, because in the Ancient World at least some sorts of texts existed fluidly rather than statically (a bit like your favourite Cookery Book in your kitchen, where, over the passing years, you have entered in some of your own discoveries ... changed the quantities here ... extended the cooking times because of the idiosyncrasies of your own oven ... written in a new recipe there ...).
Shakespearian scholars among you will know that, even after the invention of printing, Textual Criticism still cannot be avoided, because the questions of 'Actors' copies', modified within the actual process of dramatic production, and of 'pirated' editions, published from a shorthand copy, muddy the waters.
And have you ever looked at the Oxford Edition of Wordsworth? Phew!!
Talk about "fluid texts"!!!
The Authentic Magisterium of the Catholic Church has, for millennia, cheerfully accepted and employed Textual Criticism; perhaps most notably when S Jerome and, later, Roman Pontiffs were working on the Vulgate ... compare the 1590 Vulgate of pope Sixtus V; and the later Vulgate of pope Clement VIII ... which itself appeared in no fewer than three editions! Likewise, when S Pius V had the Missale Romanum revised ...
So it's Megauntraddy to be suspicious of Textual Criticism!
That doesn't mean that it's OK to behave like PF, and to monkey around with any bit of Scripture that doesn't fit ones own current personal fads.
That is arrogant ultrahyperueberpapalist Bergoglianity.