These books are not fit for young readers.

Just because a certain book does not interest readers does not mean that the fault lies in the book.

Let the reader be the judge.

In reality, translation is akin to working for peanuts, since the corresponding meaning of something in one language is often hidden in some deep and impenetrable recesses of the other. As a result, the translator is forced to search all over... Never mind that the picky reader is very difficult to fool.