I've added variants for those icons with Mp3tag v3.34-beta.8, which should work in both modes. Thanks for pointing!
As for the menu arrows, I need to leave them as they are. I unfortunately have no public API to modify their colors, and experimented with drawing my own custom version above those. This didn't turn out well (besides being an ugly hack), because it's hard to predict the actual position of the area that is acting as the menu (UI scaling and different Windows version don't make it easier).