I know that if you put a stage on certain kinds of lots, the lot will function as both its designated lot and as a performance venue -- so a Dance Club with a stage will also function as a Live Show Venue, a Dive Bar with a stage will function as a Coffeehouse Venue, and so forth.

My question is: were the University Life lots updated to serve double functions as well? If I were to put a stage inside an Arcade or Java Hut, would those function as the appropriate show venues?

Yeah I did that to in University world, it works, but the problem then my sims starting to skip schools..

So it does work. I assume that both Arcade and Java Hut function as Coffeehouse venues?

Mine was Arcade and I put live stage in it, but you'll need Bluefunk_Proprietor Placement mod to place the proprietor to work, I don't know about Java Hut, I don't remember exactly, but I did put some bars from Late Night and it works as is functions..

Yeah, those lots work as venues. The list is as following:
-Coffeehouse: Arcade, Java Hut
-Live Show Venue: Rebel Hangout, University Hangout, Nerd Shop