Now, I'm not far enough to know for sure, but didn't a mind honey incident remove one of the more likely candidates?
If you mean Aradia, don't worry, she got better. Sort of.
Now, she does seem like the likely candidate for the mysterious instigator, with the "Maid of Time" thing, and wanting to help people by creepy and inscrutable means. I'm not sure she would put up with all the time-window trolling shenanigans of the people actually doing it, but she doesn't seem like she'd have misgivings about anything either, but she's okay with a lot of things now anyway.
On the other hand, uphelpfully trolling people with useful information across time seems like the kind of thing Vriska would come up with, especially since she has a bone to pick with that Cue-ball guy and the mysterious final boss "Lord English" guy. And having misgivings seems possible in light of Hussie's growing hints that she's not the unrelenting bitch she first appeared to be. But then, it also seems like exactly the kind of thing she'd really want to do herself, which begs the question of why she's not part of the trolling, whoever's idea it was.
And of course, Nepeta is the crazy lighthearted autistic catgirl, and absolutely nothing is known about cC yet, so they're both a wash in speculation.