Okay, so with 2.1 on the horizon, I see some potential things to look at;
Cammy seems to get dragged away in the tutorial/story mode
Since the ghosts are corporealized from light, it makes sense the rocket launcher would straight up injure them. They don't seem to have a way to interact with most items, though, or Japes at least has a way to prevent them from interacting with his stomach's contents. He would have to or Zahra and Xenosheet would damage his stuff.
The two minigames so far are arcade games with the living versions of the ghosts you consume. But they seem to have ways that they could die themselves; "friend" could get blown up or run out of energy, and the Kobolds could starve to death. I wouldn't be surprised if these deaths correlated with how they were killed when entering the mansion, and the arcade games were twisted mockeries of their demise. If the Kobolds are from Cammy's world, going by the music, it would mean the Seers could potentially project their presence into two worlds :(
Japes' upgrades are tied to his soul, and he can sever them. The curses, however, have the trademark singular eye, so they are likely created by the Seers themselves, and their connection seems to be metaphysically hooked into Japes' soul, so removing them seems to require spiritual surgery that the Fire Dweller definitely isn't doing by himself at this time. They don't seem to have come close to reaching their full potential either; His soul has a red aura, but Dinostuffed says that his soul has an iridescent aura, so he likely has a connection to the "Sword" and "Star Dweller" somehow.
Though I wonder if we can get a bad ending with Japes and Cammy or if they somehow get turned into ghosts while still living. Who knows, maybe we'll get the power of friendship to revive them so we can reclaim some modicum of "patheticness".
If Japes having teeth is a new thing, the new enraged sprite is gonna look scary as hell :0