Back again... And now it appears that there actually is an issue relating to video calibration/scaling. (It wasn't just my imagination, and despite what I might have said awhile ago, I actually didn't fix it.)
Here's the story in a nutshell. As I said, I've got a Beelink MiniMXIII (original version) w/ 2G/8G, Gigabit ethernet, and (apparently) the Realtek WiFi. I just downloaded and fresh installed to a microSD card the latest and greatest 8.2-8.2.1.2 kszaq build and a proper device tree. I switched the thing to Confluence skin and did the video calibration, which I always have to do on account of the fact that I have a POS Panasonic flatscreen that does a 2.5% overscan, all the way around, and I can't disable that unfortunate "feature" in the TV. So I always have to force Kodi to do scaling (underscan?) to work around this annoyance.
Anyway, I got the video nicely calibrated to do the underscan so that all of the normal Confluence menus & stuff shows up just perfect on the screen. But then I went and tried to watch one of my ripped DVDs, and I jiggled my mouse to get the OSD to come up and overlay the DVD that was playing... which it did.
The problem is that it is clear and evident that the OSD stuff around the edges is only partially displaying. It is partly obscured by the physical edges of my flatscreen TV. In short, although the scaling (underscan?) that I set up when I did the video calibration is working perfectly, that scaling is apparently not being applied to the OSD display, when it is activated. The result, in my case, is that the OSD is mostly unusable, and most of its bits and pieces appear half-way off the physical screen.
I didn't check to see if this is a problem also for Estuary, but I kind-of-suspect that it isn't, or else a lot of people would have reported it already.
Anyway, I hope this can be fixed. It would appear that the calibration/scaling information is just being stashed in some place where the OSD code (in Confluence, at least) isn't picking it up.