I agree with @InvidiaRed on this one. If it’s a demon with the ability to think in human terms, then it’s not bestiality. If it’s an animal with the thought processes of an animal, it’s bestiality.
Well what I mean is a human transformed into a demon with scales or with the head of a dog who instead of speaking like a normal human, they speak in simplistic terms.
Tough question. My first thought was whether the other could articulate consent.
However, when it comes to tagging… it’s better to (slightly) over-tag even if you’re unsure as these are warnings to the reader. You can qualify it too, at least at the top of the story with [Beast] (werewolf).