You and I may think it is absurd to copyright languages; unfortunately Paramount doesn’t, and has forced someone to pulp their Klingon Martial Arts manual in Klingon.
The safe thing to do is to approach the Klingon Language Institute (Page on kli.org): Paramount have designated them as a licensed user of the language, so they can publish text in Klingon safely.
EDIT: looks like the long awaited lawsuit is finally happening. Paramount v Axanar 2-15-cv-09938 CD CA 2016-04-27 35-1 – Brief of Amicus Curiae.pdf