In the Hungarian Crown lands, esp. Croatia, Latin remained in official use well into the second half of nineteenth century.
However, nobody ever dreamed of reviving it as a widespread spoken language.
I can see a surviving Austrian Empire or PLC doing that but probably the POD needs to be before 1750 at latest.
No way it can happen in Italy, not with a Modern Era realistic POD. It's not like Italian "Founding Fathers" picked a linguistic variant and enforced it over a previously "Vulgar Latin" speaking population. Tuscan was already the language of prestige and literature in most of the peninsula, since 1500 at least, (though most of the people outside Tuscany did not speak it) and nobody after that would have supported a "back to Latin" stance without major changes.
I can see a totaliatarian regime harking back to Rome trying such a thing, I hardly can see it successful.