"Horror comedy" is not "horror". And "horror romantic comedy" is even less so. That's the point. There's nothing scary, no extreme violence, no gore, nothing truly disturbing etc. (the main elements of the genre) in this manga. There are only shallow, superficial, aspects of "horror" (eg there's a "spoopy" ghost from time to time, but it doesn't really scare anybody reading the manga).
Again, if you try to call Scooby-Doo "horror" people will laugh at you. But if you say it's "horror comedy", then folks will go "oh, ok, yeah, you could call it that". It's at the level of wearing a blanket to pretend you're a ghost on Halloween. It's just "horror themed", which is far from being actual horror.
Anyway, it's just semantics what you actually wanna call it. The point is it's a chill cute manga and nothing in this chapter (or before) changed that, even though out-of-context it could sound bad ("a ghost possessed a girl with a mysterious void-like hole in her and then threatened to beat up another girl!").