Of course, there's polysemy in every creative work. Plot points and set pieces are open to more then one explanation. So, what I say is not the only interpretation.
Nevertheless, the way Katie Isabelle delivers the line "It wasn't a beep bear, there aren't any beep bears near here!" and the fact that the moment earlier she was pleading with Brigitte to give her some rational real-world explanation for what happened, only to reject the only one Brigitte gives.
Let's look at what the sisters know. They know it's a full moon (they were outside, and Brigitte confirms they both knew this in the bathroom stall scene). Brigitte knows the creature tossed her fifteen feet through the air, at least. Ginger knows it was powerful enough to kill or incapacitate her, like crush her bones, but it didn't; though it had control over her for long enough.
Instead, it wounded her superficially in as many different parts as it could. Perhaps it was playing, and perhaps it wanted to mate with Ginger (eventually) so tried to see she was thoroughly infected. Meanwhile, who knows what Ginger saw in the time it had her to itself?
Part of the artistry to any scene like this is to make the most logical explanation (she was just traumatized) the explanation that you'd have in any (somewhat) similar animal mauling in the real world. But at the same time hint in subtle ways that things are not quite what they seem. Not only in plot points, but in character behavior.
There's one other thing that bears repeating (no pun intended): Ginger swearing Brigitte to secrecy about it was something that Brigitte found very odd, and not just ill-advised, and Brigitte knew Ginger's relationship with their Mom better than anyone.

To be fair on your first point, you could also pin that to suffering a traumatic experience. I mean she was just attacked.