Much of the library still lies unexcavated.
I've read one theory that says there could be a whole Latin section of the library that remains to be found since it was a custom in libraries then to have a Greek collection and a Latin collection. Although, from my perspective, the Villa was a private collection so it doesn't necessarily have to follow that pattern.
But the possibilities of what remains untranslated and even undiscovered - not to mention what was burned and discarded before they knew what they had! - boggle the mind.