Fr Zed reveals that Notitiae has published a list of corrections to the Missalis Romani Editio tertia. They include corrections of grammar.
I have been shocked over the years as I looked at the propria novissima published in Notitiae to find that, time and time again, IV form errors in latinity jumped up at me off the page. I recall there was a nastiness in the first form of the collect published for S Edith Stein; but the lectio for S Padre Pio was a tour de force in the absolutely disgraceful.
The 1869 Breviary I use for Dominical and Festal Vespers ... not unlike the 1950s Missal I use over in the church ... has a nice bit at the front by Victor Augustus Isidorus Dechamps, Dei et Apostolicae Sedis gratia Archiepiscopus Mechliniensis, Primas Belgii, Sanctitatatis suae Praelatus domesticus et solio pontificio assistens, all about how he has obeyed a decree of Urban VIII to have printers' proofs carefully checked per revisorem a nobis deputatum. Before the Council it was inconceivable to come across even minor typos in a liturgical book. Now they abound; just one big example: if you use the Second Edition of the Liturgia Horarum, check through the patristic reading for the Cathedra S Petri in the two versions in the two volumes in which it is printed (it can come either before or during Lent). And not just typos galore, but substantive errors in Latin originals.
!n 1998, as Lancing College celebrated its 150 years, we sent off two letters asking for blessings; one, in formal Byzantine curial Greek, to the Ecumenical Patriarch, one, in equally formal Latin, to the Sovereign Pontiff. The former replied most graciously with several pages in the same style of Greek; the latter replied not at all. My conclusion was that nobody at all knows any Latin at all in the Vatican.
Except, of course, for Benedict XVI. He's no fool. He took care to write the new Prayer for the Jews himself.