Currently there's a relation in place: [artist] taught at [place]
Occasionally/often enough, I come across biographies where an artist is/was school principal (of a conservatory), but not in an actual teaching position. So "school director at", "principal at", "director at" (or a similar phrasing) would be a welcome addition to me.
(attributes "instrument" and "subject" wouldn't be required for such a relation I think)