I may enjoy trying different icons and themes, but I have absolutely no idea how the themes work or how the files are written.
So I'm glad we have people in this community to pass the baton to.
I'm happy to have greybird-thick remain as the default theme for MX since it looks like there are upstream solutions to the bugs. It's a very respectable theme.
I was just surprised that the so-called officially supported theme for XFCE wasn't working well with even the printer applet, which is a pretty common program. I never noticed it previously because this "Windows Printer via SAMBA" page of the applet window is not one I'd ever clicked on.
As for sudoku, I like doing at least one a day if possible. I find that gnome-sudoku has really challenging ones, more so than KSudoku. I think I've tried the ftlk one before and didn't really like it, but maybe I'll assess it again.
But that's why gnome-sudoku being almost unusable in greybird made me seek out other themes. I tried the Mediterranean series of themes, which I also like, but they had the same problem.