Hello Pierre,
This is helpful. I deduce from this that you can only use revert on bound-details as a while if you override it as a complete alist to begin with, not as separate overrides for each sub-property as I had. That's an important thing to know.
Of course, to revert the other overrides, such as font-size, back to the system default, that would need a separate revert as well for these. I can find all the system defaults in the lilypond source code.
I was hoping there may be some sort of \reset command, but this is a figment of my imagination.
Andrew