It seems that I'm probably going to be doing more engraving after all.
I have a comment about the documentation. I wanted to add the same articulation to all notes in a music _expression_, and found http://lsr.di.unimi.it/LSR/Item?id=82 which does exactly what I want.
I noticed that it uses a function called 'map-some-music' and I can't find any reference to this in the Extending or Internals manuals. It seems to have the function of traversing a music _expression_ and doing things to it - but is there a definition of its function anywhere? It would seem to be very useful.
A happy 2021 to all Ponders - may it bring vaccinations,