So Zelle, Marius, and I were left alone together yesterday, when suddenly we realized a possible, though maybe not entirely probable, meaning for Courfeyrac's name. Multiple, in fact.
The first one noticed was that Cour looks a bit like cœur, which, as most of you probably know, means "heart," and also "core" (and some similar things, but those are the main ones). Courfeyrac is described as the center, or core, of the group.
It was also pointed out that "cour" is literally "court," and could be a reference to his noble heritage, though it could also mean "courtship," which would suit him so well.
They "feyrac" part could be a reference to Chateau Fayrac, and thus another reference to Courfeyrac's family heritage, but I'm not sure it would be well-known enough back then that readers throughout the country would know it was an allusion, and, well, an audience has to be able to get an allusion for it to be effective.
So, all of this may be out on a limb, or maybe even just a rehash of what others have said and that the three of us just hadn't come across, but an interesting thought. And since Hugo seems to name his characters with either puns or allusions, having a character whose name includes both maybe isn't too far out there.
Also, sorry to link to an article in French when I had to use google to understand it myself.