I believe those were both mentioned... in Fleet Action. Let me check...
Yep, Fleet Action. Both ships are referred to in the context of Hunter's visit to the Landreich, and the bizarre collection of ships that the Landreich uses.
The Granicus-class is said to be a medium corvette, "a line discontinued more than twenty years ago". What does this tell us? At the very least, we can tell that the production of Granicus corvettes was discontinued at some point before 2648, and most likely between 2643 and 2647. The logic behind this: if the date referred to had been within about a year of 2648, then it would have been just plain "twenty years ago". If the date had been more than five years before 2648, then it would have been "nearly thirty years ago". So, "more than twenty years ago" gives us a window of about four years. But there's a caveat... this is Hunter's internal monologue: it's meaningless unless you assume that Hunter has encyclopedic knowledge of outdated ship designs. In addition, we don't know what "discontinued" means. It could be either the moment the ships were retired (but this doesn't seem too logical), or the moment the ships were put out of production (more reasonable). All in all, we know the ship is old - but we don't know how old it is, and if it was around in 2639 (but it seems like a safe bet).
The Falcon-class is referred to even more briefly. Yes, it's a light corvette, but the ship doesn't put in an appearance. Hunter simply sees a Ferret, which had been refitted with the engine from "an old Falcon class light corvette". We can't tell anything from that, really. The Ferret itself, incidentally, is an early Ferret A - which by itself must be at least thirty years old! (yes, Ferrets were around in the Enyo timeframe)
.