Leo Elijah Cristea has posted some thoughts and observations about made-up languages in fantasy (and science fiction) over at Fantasy Faction. The bottom line: nobody who doesn’t have a Ph.D. in linguistics is going to do it as well as Tolkien, and even if they could, that’s not what fantasy readers want any more. Characters are everything, and the world-building must serve the characters (and, of course, the plot).
For Children of Pride and its eventual sequels, I’ve roughed out a couple of constructed languages. Esrana, for example, is the ancestral language of many of the fae kindreds of western Europe. It holds a place similar to Latin in the Topside world, especially a few centuries ago when Latin was a “prestige” language spoken by the educated elites. There are some characters (and locations) in Children of Pride whose names are derived from Esrana, just as there are people and places today whose names are derived from Latin or Greek (Julia, Gregory; Indiana, Philadelphia, etc.).
Not yet seen in print is Wechakáhli, the language of certain dwarfish clans. I worked out some of the details of this language just to play around with a language spoken by beings whose vocal apparatus is not entirely the same as that of humans. Other than a handful of vocabulary and a bare-bones grammar, there’s not much to it.