I was surprised how quickly (by my standards anyway) I completed the grid, but of course that was the easy part. When I looked the theme up I had to check several times that I had the English page for the relevant Wiki article, for all the sense it made to me. I think I have worked it all out now, though I can't pretend I have anything more than the most superficial understanding of the theme. Once again, the Internet comes to the rescue!
I have no idea what, if any, significance the unclued answers possess, but that doesn't seem to affect the final result. A very good puzzle, which I quite enjoyed even though I am totally out of my depth in this field.
Still working on it.
Davebro - I can well remember the sense of triumph when I solved my first Listener CLUE, back in the Listener days! It took years before I actually completed a whole puzzle, then two consecutive ones. After half a century of trying, I am at the stage of submitting every week, but with several silly mistakes a year. It has become an obsession, of a good kind, a pleasant part of my life. Stick with them and you will come to love them too.