From what I know of the renaissance people viewed it (to name one aspect) as if the quality of the Latin was diluting. In the carolingian renaissance however the Latin was getting back to its roots. How did the people of the renaissance to this fact. And in a lot of other aspects to. Agreed that the middle ages never really achieved the greatness of the Romans but still the cathedrals they built are fabulous.
I should make a brief comment here: the "Carolingian Renaissance", unlike the Italian Renaissance of the 15th century, wasn't described as a "renaissance" as such; the term is a product of later scholars attempting to argue for the Carolingian period as one of increased literary and artistic production and increased interest in Roman literature and art. It's also important to note that the Italian penninsula had a very different cultural trajectory in the middle ages and early Renaissance than northern Europe, largely because of the degree to which it was in the orbit of Byzantium and the Islamic world, so I'm not sure the Carolingian Renaissance would not have mattered as much for Italy. I'm happy to elaborate on this if you like of course.