The Wiki is not very helpful there, though.
What I'm trying to achieve is add nodes as a filter in facets. Could someone give me a pointer how I would go about this?
Indeed I had assumed that "nodes" were a core feature, not a plug-in feature
If that's not so, maybe adding nodes, or support for different libraries (speech/music) would be helpful. Even a plugin that generates a separate node for one or more user-defined tags (speech, audiobook, etc.) would greatly improve usability.
this would be somewhat useless, because every library viewer has something that works exactly the same way nodes do, it may just be called different, thus you can always split your library into subsets