It depends on whether or not Extended Luminance Range for Auto-Exposure is enabled in the project settings. When enabled EV100 is used. None of this is really relevant, this is not an auto-exposure problem.
Assuming you did this in your project folder and not the engine you should be able to just delete them and the engine will fall back to the defaults. Should probably back them up though in case I’m mistaken.
Well you haven’t done the most important thing which is what I told you in my very first reply: Look at the Lumen debug views.
Per the Docs:
Whenever you have a problem with Lumen the first thing you should do before anything else is look at the Lumen debug views. They give you Lumens view of the world and are the single most important piece of information you can have about why the lighting is behaving unexpectedly.