Is there a story (Talmudic or folkloric) about G-d revealing a future scenario to Moses where his words are being discussed/studied at a Yeshiva--and Moses doesn’t understand what they’re talking about?

Shalom, Yes, there is such a midrash (= a Talmudic accounting) of such an event. It can be found in the Babylonian Talmud, tractate Menachot, page 29 folio b. It says, in a loose translation, as follows :- R’ Yehuda said in the name of Rav: When Moshe ascended to the heavens, he saw God sitting and tieing crowns to the letters [of the Torah]. Moshe asked, “What’s the hold up [i.e., why can’t you give the Torah as is]?" God replied, “there will be a man in the future, after many generations, named Akiva b. Yosef, who will find in every jot and tittle mounds of halachot [laws]." Moshe said, “Master of the Universe, show him to me!” God said, “Turn around” Moses went and sat in the eighth row of students in R’ Akiva’s class, and had no idea what they were saying. His strength deflated. The class asked R’ Akiba about a certain matter, “From where do you know this?” He replied, “It is a Law transmitted to Moshe at Sinai". Moshe’s mind was put at ease. Moshe turned to God, “If you have someone like this, why are you giving the Torah through me?” God said, “Silence! This is what arose in my thoughts!” Moshe continued, “Master of the Universe! You’ve showed me his teaching, now show me his reward.” God said, “Turn around” He turned around and saw that R’ Akiva’s flesh was being weighed out in the marketplace. Moshe confronted God: “This is Torah and this is its reward?!” God said, “Silence! This is what arose in my thoughts!” Of course, now you have this source, I am sure it will only increase your desire to study it further - may you be blessed in all your Torah endeavours! Blessings