I think the problem actually lies with the English, not with the French. “Library materials” in English is different from “documents de bibliothèque”. “Library materials” in English opens up too broad a definition. It could include anything that's used in a library. The English version needs to be brought down, whereas the French version, which speaks to the “documents de bibliothèque”, clearly identifies it with the product of a library.
On October 26th, 2010. See this statement in context.