I've figured out most of that already. Nile doesn't "never go away". There was a hint text that says "you have to let her in eventually" and I figured based on her personality that she wants one thing, so I figured out that if you just stare at her after opening the door, she leaves. I understand the parry mechanic, but having it shove you out of whatever you're doing at that moment is really disorienting. Poppi's minigame is probably the worst for me. Once the cameras are messed up, I might as well restart because I can't get to the generator to keep the doors closed while I'm frantically searching for the eyeball thing, and I can't tell the trigger for Poppi. It seems like it's somewhat based on corruption, but also time? I can't tell. As for sammy, I'm sure there's probably a tell for glitchy vs non-glitchy, but that's pure random chance. The other thing that really messes with me is that the doors just sometimes start opening and closing on their own. I don't know what causes that or how to deal with it other than spamming them, but if it randomly happens at a critical time, then I just lose.
Looking back now that I'm not tilted, I think the best strategy is probably to just shut the back door permanently because I don't believe there's any enemies that can force that one in specific open and frequently boost power. SHE only appears in the left and right doors, Maddie I think only appears in the right door, Ari only gets mad if you mess with stuff.