It's been 18 years since the last time I dropped out of graduate school, but a lot of the things I read are similar to things that grad students would read. I've spent a significant portion of my life in university libraries and used-book stores; I did that before I was a university student, and between the periods when I was enrolled in one university or another, and when I was enrolled I spent a lot of time in such places researching a lot of things which did not have to do with the courses I was taking at the time. At the moment I'm waiting for a volume of letters between Leibniz and Wolffto arrive via UPS, a title whose audience, I'm guessing, consists mostly of professional academics; the tracking information indicates it should arrive today.
Latin letters: the German title of the book is Briefwechsel (in lateinischer Sprache), Correspondence (in the Latin Language). I suspect that the subtitle in parentheses may be meant to indicate that Leibniz and Wolff also corresponded in other languages, but the present volume presents only the Latin letters. I ordered the book because of my interest in Leibniz, with Wolff's name ringing only the faintest of bells; after I ordered it I checked the Wikipedia article on Wolff -- Christian von Wolff -- and it says that he was the most eminent German philosopher between Leibniz and Kant, and that it was he who introduced the use of German as a language of scholarly instruction and research. (So, it was him! He's the one!) Wolff lived from 1679 to 1754. There was still a lot of German scholarly writing in Latin after him -- see for instance this collection of articles by August Boeckh,written between the 1810's and the 1840's, or the two pieces in Latin written by Nietzsche in the 1860's included in this collection;but both the Boeckh and the Nietzsche are articles having to do with Classical literature, where it's only to be expected that the use of Latin as a vernacular would persist longer than in other fields.
Also, it seems to me, although as yet I have no way at all of proving it, that academic papers and lectures must have been written and read in German at least now and again before Wolff.
Still, I don't see any particular reason to doubt that Wolff at least greatly popularized the use of German and the partial abandonment of Latin in German universities. It seems to me that there must have been some controversy over this; I'm picturing polemics published for and against the use of German in academia. I'm picturing most or all of them written in Latin, on both sides of the question. Reader, you may consider me to be already actively looking for those polemics exchanged between 18th-century academics. I'm on the side that lost, and I'm annoyed with those earlier scholars who lost the cause. I'm picturing pro-Latin polemics full of faulty reasoning, ad hominem attacks, reactionary politics, contempt for the lower classes, and a pronounced lack of charm in general: with some exceptions, a good cause badly argued, and on the other side, very bright and good men, and perhaps even some ladies, holders of salons perhaps, arguing brilliantly and movingly on the wrong side. Cheered on by horses' asses like Rousseau and Paine.
Now the cause of the revival of Latin is a positively Quixotic one, argued by a few weirdos such as myself. I don't think it's impossible that Latin will one day once again be a widespread common language of academia, re-establishing a international, non-nationalistic Latin culture, and not just in Classical studies and related disciplines, either, or even in wider circles than academia; but that's mainly because I think it's logically unsound to make predictions about human behavior using the term "impossible." Even I admit that it's extremely unlikely.