They’re walking a knife edge. So far there is nothing that is completely supernatural - just highly improbable otherwise, like it’s technically possible to come across an orange on an ice field, just not very likely. At all.
How they resolve it will make this a worthwhile outing or a pile of shite. There’s always the ‘Stephen King problem’ where revealing the boogey man suddenly makes everything ridiculous. But he, and those like him, at least commit to a supernatural element. This could go wrong both ways.
Tbh - and to save you the time, don’t bother pointing out the flaws, I know it’s a failing on my part - I hate anything that isn’t realistic, from ‘serious’ magical realism to fantasy hokum. Or at least could be realistically explained, whatever the required stretch. In fact I actively like that kind of stuff, because the world is mysterious, it’s just not magical.
If this goes sci-fi , I’m out.
Until the collapse though, I still like it.