1. Okay, I can see your point. Some of the more environmental effects may be the effects of the mode and not necessarily the characters themselves.
Headless: Glad that was explained
2. I don't know. I know it could be the environment, since it has Creation, but it just feels more likely that it's the characters themselves.
And I forgot we had Animal Manipulation
Headless: Thing is, it doesn't seem like they are created by Chica, as they are already in the background at that point. Additionally, is having an infestation of bugs
Animal Manipulation? She isn't really using them in any noticeable way, coach roaches or the large bugs in the background. It is far more likely that Freddy's is just a disgusting place infested with bugs, rather than Chica being responsible.
3. Jack-O-Chica=Minor Light Projection, possibly Resistance to Fire (Is on fire and isn´t affected by it) would be fine. Forgot about it. Oof. Would say Foxy's is a tad more....hm but yeah.
4. I mean, it's made to blend into the darkness of the vents. You really only ever see the eyes. More likely than not, it's a shadowy clone.
Headless: Made to blend in is
Camouflage. Imo, it is just camo.