Ernest Miller analyses the question, "Can the Klingon language be copyrighted?"
However, can you really copyright a language? You can copyright a dictionary, certainly, but can you copyright grammar? I'm not sure you can copyright grammar at all, since it is a set of rules regarding word usage. Grammar is an idea, that can probably only be expressed in a fairly limited number of ways, even if fanciful.
Additionally, each Klingon word would seem to be too short to qualify as copyrightable individually. I don't think that a list of words in a dictionary format would be copyrightable under Feist. So, I'm not sure at all how one could copyright a language. The individual descriptions of the words might be copyrightable, but as long as they aren't exact copies, the idea/expression dichotomy should provide only limited copyright protection to Paramount.