As for the truly modern language, it is very difficult to find a book that is in the public domain together with its translation. Often original books in modern language, being in the public domain, have a translation done much later for which its copyright hasn't yet expired.
I dream of modern fiction that is released into the public domain by its authors from the very beginning. Let them be amateurs, I don't think it's important from the point of view of learning a language. But its translation is also required to be in the public domain. If a translation is done by an amateur it can be of poor quality (as often, but not always, typical for amateur work) and thus not very suitable as a basis for a parallel text.