Oh well. Behold my updated MangoHud configuration which isn't visually different on any of the presets I use for screenshots, except that I've made some executable-specific copies of the configuration file that have custom text for a program version where an automatically detected Wine/Proton version would otherwise go.
By the way, running GZDoom with MangoHud makes it crash on exit. I suppose I should be glad it doesn't crash before exit. But maybe I did something wrong when I compiled/installed MangoHud. I fucked around quite a bit in figuring out how to get mangoapp working (which of course I never actually use).