You can also bind the Ghoul King, who is neither drone-derived nor flying. I'd suggest that in addition to etheric versions of drones with the mysterious drone signature or some close approximation of it (Titanic Mole), the other big grouping seems to be entities who come somehow or other from art: various opponents associated with the Artist and also a bunch of Art Museum opponents. (I had originally been thinking only about the Artist; Crypto pointed out that art in general correlates with being susceptible to binding.)
Dazzling Cloud is a bit of an outlier, although you can't fully bind it. Not quite sure how that fits in. The description of the tome mentions "demons", but the tome's definition seems more restrictive than Matsuo's.
I agree that it does seem really weird that we can't bind flying eyes. Somebody straight out asked about flying eyes in Podcast 29:
Q: Could we bind Flying Eyes?
A: I suppose that's not entirely unreasonable. Not sure why that's not in there now. I'd have to double check some facts about the helidrones.
This suggests you can't bind Flying Eyes, although 2013 was a while ago, so it's possible Kinak went in and made it possible since then.
Another podcast nugget, from Podcast 46:
Q: The tome of binding seems pretty well-spaded out, as we've killed nearly every monster available with it. Any secrets still lurking behind its innocuous facade? Anything to do with binding humans?
A: It does have limitations on what it can bind. Those follow its own internal logic, not sure if that makes sense or not. I’d be surprised to find it binding humans, not surprised to find it binding things that look like humans.
This suggests that we somehow can (with the unfound Charnel House skill?) or someday might be able to bind ghouls.
One other thing I notice about the tome is that there's a sort of gaze theme. Flying Eyes seems like they at least should be bindable. You can bind the Evil Eye in the Park (teaches the Evil Eye technique). And you can try to bind the Starry Gaze in the Museum (which eats Evil Eye to give Starry Gaze).