I’ve found quite a few things talking about this in the Blighted Village, one of which was hidden pretty well. But I’m not getting any kind of journal entry about it, can’t talk to any NPCs about it, etc. It kinda feels like there should be something more here but it’s been cut or just very well hidden.
I suspect it’s been cut. Either that, or it’s just meant to be a sort of “yeah, Moonhaven was always kinda fucked, between the swamp hag, incognito Red Wizard and Underdark entrance right next to the water source, not exactly safe for children.” :P
Maybe once upon a time they were part of some sidequest connected to Ethel, the Red Wizard or the invading Sharrans, or maybe it was just atmosphere, who knows. /shurg