How do I translate the books?

Tutors are special characters that you can find throughout the game. They will for example give you tasks to bring them artifacts of certain levels and each one of these can teach you a language. They require Spintria to teach you the language, which is the special currency you get for finishing excursions or missions from these characters.

Primers on languages can be found by spending gold in Morland's Shop and hoping to find such a primer. They can then be researched to learn the language and afterwards you can translate the books that are written in this language.

There is no other way to translate the books.