Well maybe not all red ones, since I remember that blinking base switch is a major exception, but medieval Q switches that are red are distinct from brown ones in that they're shootable, at least in official levels.
Finished it, haven't encountered any other real problems. There are distinct messages in Doom for locked D actions and locked S actions - one prompts that door can't be opened, the other that object can't be activated. It seems that new messages don't have this distinction, likely duplicated. I remember more than one occasion when a locked button told me that a door can't be opened.
And one of my vintage retarded nitpicks: MAP07 sectors 1416 and 1467 - floor too bright? Not sure if intentional. This is just something I accidentally spotted without looking for any of such things, so I don't know if there's anything similar in the vicinity.
Lighting is probably the most impressive thing about this wad, besides "scripting". I'm usually not fond of complicated lighting, and a lot of the attempts to emulate newer engines' smooth lighting look off, but here it was pulled off really well.