Last weekend I created three book items, turning them into objects shortly after. I viewed both the items and objects on my human character and they seemingly worked fine. Coming online today on a blood elf character and looking at the book objects they seemed to have been translated into a different wow language. (Thalassian I think). I just logged onto an orc to see if the books would translate into orcish but it was still the same as it was on my blood elf. So I reckon the books differentiate between Horde or Alliance.