By the power of modern linguistics, quite a lot is known about the early history of Latin: for quite a while it coexisted with close relatives like Oscan, Umbrian, and Faliscan, as well as the unrelated Etruscan. Several Classical Latin words show evidence of mutual influence: Oscan/Umbrian lupus "wolf" displaced native Latin *lucus, for example.

Cicero, Varro, Gellius, Suetonius, et al, were clearly familiar with the Etruscans and their language, whether or not they actually spoke any of it. But I can't think of any mentions of other Italic languages in Latin literature.

So my question is: do any Latin authors, of any period, talk about Oscan, Umbrian, Faliscan, or any other Italic languages apart from Latin? For example, does any grammarian mention that some "dialects" use p where a true Roman would use q?