I said earlier that I'd only ever had one Njerp encounter at my homestead. Of the 4 characters that I've been running now for over a year(RT), the only one with such an encounter just had another recently. A Njerp came around who was tripping the traps next to my homestead (I'd read someone's account of Njerps doing that). Now, later, a band of foreign traders kept bumping into the surrounding fence at the same homestead for about 4 days. (pathing problems?)
So, in over 800 hours of play of 5 characters (4 still living), that's the totality of homestead encounters with humans, three, and all at the same homestead.
I guess my point is that IF there is some abnormality in Njerp frequency, I feel I would have seen it around the places I've settled, too. I'm leaning toward simple RNG, like the one character I run that has encountered wolves on so many occasions, out of proportion to any of my other characters.