Not sure that library creation is doable (been ages since I looked). I always found it easier to manage them in a file and move the materials from file A to file B by assigning them to a family in file A, and moving the family into file B.
Yet an update with +20 new nodes…
Nodes for BuiltInParameter. Nodes for copying and transferring elements between different document. Nodes for opening, save and closing central files. Nodes for linking files into documents.