One of the most common biblical manuscripts used to make our modern English translations is known today as the Nestle Text. Yet it was Prof. Eberhard Nestle himself who warned us in his Einfhrung in die Textkritik des griechischen Testaments: "Learned men, so called Correctores were, following the church meeting at Nicea 325 AD, selected by the church authorities to scrutinize the sacred texts and rewrite them in order to correct their meaning in accordance with the views which the church had just sanctioned."
Even if true, this seems wholly irrelevant to the topic at hand. But
is this quote true? From what I can tell, the answer is no.
This "Einfhrung in die Textkritik des griechischen Testaments" you claim he wrote is, as far as I can tell, unknown outside of this blatantly copy/pasted quote you provided (also, it doesn't even spell Einführung right). He did write the similarly titled "Einführung in das griechische Neue Testament" (found
here) but I can find the quote nowhere in it via a search. Granted, it's in German so I have to guess as to the original wording, but "325" and "Nicäa" (German for Nicaea) are obvious enough, but a search for those phrases in the book turn up nothing similar.
Now, that work was translated into English, available
here. This translation is named named "Introduction to the textual criticism of the Greek New Testament" which when translated into German produces "Einführung in die Textkritik des griechischen Neuen Testaments" which is closer to the title you produced but still not there--furthermore, this is a back-translation of a non-literal translation. Perhaps that's how we got that, someone took the English title and tried to back-translate but did a poor job of it.
But this, too, turns up nothing. "325" turns up nothing relevant, nor does "Nicaea" or "Nicea." In fact, if you look at the Index, Nicaea doesn't show up at all, even though other councils do! A search for other phrases in the quote you provided offer nothing like the quote.
Now to be fair archive.org's search function isn't perfect so it could have missed something. Still, I've done my due diligence, so it seems the onus is on you. As you're the one who offered it, can
you demonstrate that this quote is authentic? Show me what page it's on--it can be either a German or English edition.
St. Jerome wrote: "They write down not what they find but what they think is the meaning; and while they attempt to rectify the errors of others, they merely expose their own" (Jerome, Epist. lxxi.5).
At least this one is a genuine quote, though what it has to do with the discussion is unclear and thus I'm confused about what point you're trying to make. The context, at any rate, is that Jerome appears to be putting this criticism towards a specific group of copyists rather than as a general criticism ("I have given them to your servants to transcribe, I have seen the paper-copies made by them, and I have repeatedly ordered them to correct them by a diligent comparison with the originals").