I expected that 32 would be the max, 16 in each monitor, 31 on the laptop running without an external monitor. When I discovered that I could go past that, I stopped at 40 for experimental purposes (41 in two monitors).
If I can make something that scales to 40, then it should handle 20 easily. Having to physically switch to each and every desktop to find a desktop by name is not practical.
I can put a TextEdit window in each Desktop or a Notes window, or Finder or a lot of things, and I can quickly switch to that Desktop by activating the window by name from an easily accessible list. But I use TextEdit and Notes and Finder a lot.
So I've been expecting that would have to dedicate some unused but minimally functional app to this purpose.
It started to look like KBM's HTML Prompt could do it, but that turns out to have been wishful thinking. It could generate the ideal geometry window, but it can't list all open windows by title. And its not good about windows being moved from Desktop to Desktop. I haven't yet tried building a script that creates an HTML Prompt window on multiple Desktops, but when I create multiple windows on one desktop and try to move one of them to another Desktop, all the other HTML Prompt windows come along with it. That suggests that part of the listing problem is that they are not really separate windows.
I suppose I could build my own app (theoretically, I'm not that app builder, yet) that has no other purpose than to display a title and list all the titles of all windows -- provided that it could also do what TE and Finder and Notes can do, but a lot of apps can't, and that's have each window stay in its original desktop through a reboot. That's the original question in this thread, an app that is only a titlebar where I can list the titles and which hopefully stays on its Desktop when rebooting.
Thanks for the reminder about the Script Debugger Forum. Maybe I should post the question on Ask Different or Stack Exchange too. All the "build your own app" tutorials that I have found don't go near the topics that I need.
And then there's AltTab, Which, and Contexts, mentioned above. AltTab isn't what I need, for reasons described in item #32 above, but the others might get me there, I haven't looked yet.
Again, thanks to everyone for thinking about this.