Yeah, it’s kind of crazy I haven’t run into a similar need for this yet.
As an inefficient workaround in the meantime you could make a “1 TapTool, 1 Renderer” setup i.e. have a taptool for each glyph/renderer (and of course write some function to expedite the initialization/generation of the CustomJS component attached to each). Not ideal obviously but if you only have a few it could be viable.