If you're asking if mythicals can reproduce in the hotel, then the answer is yes. They can, just the same as humans.
If you're asking how mythicals reproduce, that's a longer answer and I can get to it later today if that's what you want.
Sorry for taking a while, I was busy with irl stuff.
In short, some mythicals originate from humans being modified to be more animal-like, and some were animals modified to be more human-like.
P and Argos, for example, both originate from lineages of humans who were transformed. As such they can still have kids if they pair up with humans, and sometimes the "mythical gene" can skip a generation.
Meanwhile Themba and the grootslangs do not descend from humans in any way, so they can't have kids with humans.
That's what I meant for the longer answer.
if the hotel can already identify such a thing, it's then just a matter of writing a contract. like, make some kind of room that is only accessible if you have certain characteristics. we know the hotel is capable of such tricks, like making sure you can get back to the lobby if you think of it. or get you somewhere specific if you take a specific combination of directions. the layout of it doesn't need to make physical sense of it's locations.
I wondered how human detection could be used in some way or some mechanism that benefits the hotel or can be helpful to someone in some way. Like what good can be squeezed out of it. Maybe there's a practical use of it for security or safety or for everyday purpose or something. It's got to be something it could be useful for other than just a rare thing like determining one's origins.