I were there in the late 1980s - early 1990s, and the subject never came up (over the course of about 3 years or so).

At today's STAS here you see the 3rd year's curriculum.  As you can see they have a course of Cosmology (combined with Psychology!)
https://stas.org/en/seminary-curriculum-30107.

Recognizing the influence of Fr. Paul Robinson, SSPX who promotes Big Bang and Old (as in billions of years) Earth, I can only wonder in horror about what their Cosmology course entails.

[th]First Philosophy[/th] [th] [/th]
Scripture I	2h
Cosmology and Psychology	3h
Apologetics	3h
Logic	2h
Church History	2h
Latin	4h
Liturgy II	1h
Total	17h

That said, any idea why the subject never came up?  Any idea if there was any sort of unspoken (openly) consensus about these matters?

I juist don't think anyone really gave it much thought ... and I presume just took the modern heliocentric / barycentric / vortexing cosmological model for granted.  I certainly did, and I didn't start giving it much thought since the subject came up here some years ago.  Nor did I think I should care very much, as it was a secular matter, so I thought, and not really a religious question.  So this was before The Principle came out, based on some posting here on CathInfo ... almost certainly by cassini.  By the time The Principle came out, in my case he was preaching to the choir already.

As for FE, I never really heard about it much until a few years ago some "FlatEarthTrads" started posting here.  Matthew relegated them to a subforum, and that probably led to delays in my own personal awakening, but every once in a while I'd remember it was there and so poked around.  I recall thinking it was pretty dumb, but then caught myself thinking that (I introspect that way), and so I forced myself to be intellectually honest and give it a chance rather than dismiss it without examination. I think that's the problem with many people regarding many topics, where they have some ulterior motive for dismissing it, where you're pre-convinced that it's wrong or have some emotional animus against it, etc.  I refuse to do that, no matter how "crazy" someting might (at least initially) SOUND to me, since that perception could in fact be wrong, due to all the programming, and I have been "awakened" on SO MANY subjects over the years that I've come to the conclusion that if their lips are moving (or their fingers typing), they's almost certainly lying, to one degree or another.  So I said, "I'm going to honestly, and with an open mind, consider what they have to say."  Well ... took about 2 years, but they convinced me.

I saw an interview with Dr. Sungenis before his FE book, and he made the same comment, that when Kolbe asked him to write something to refute FE, he thought that it would just be so stupid that he could do it with a tiny pamphlet over a weekend.  He admitted that these guys made some solid points that are very complicated and extremely difficult to refute, and end up having to write 100s of page and (IMO of course) failed.  Yeah, it's not just some crackpot nonsense that can be dismissed with the wave of your hand, despite how much a lot of people wish they could and then pretend they're doing but just huffing and puffing and pretending it's all crazy while refusing to actually dig into the problem with an open mind.