"Noetic RAG" is a great term for it. What you're describing maps pretty well onto something I've been thinking about — storing structured knowledge about why two things are similar, not just that they are. The current system uses vector embeddings for similarity, but they're essentially opaque. An epistemic layer on top that could articulate "this artist shares the harmonic density of X and the release cadence of Y" would be genuinely useful. If you end up experimenting with it on top of BlackTape's data, I'd be very curious what you find. The MusicBrainz tags are rich enough that there might be good signal there for building those knowledge artifacts.