I don't have the map at hand, right now, but isn't "the land of Erak"/Bramwald environs supposed to be the implied setting of "Adventures in Fantasy"? :) That's where Bleakwood would be located.

Yeah, kind of always assumed this to be the case. - Like, for whom was Arneson writing Adventures in Fantasy, at that moment? Likely for his Blackmoor crew, or as a convention accessory. So, him using a "pocket setting" from a BM background makes sense.

Well, for me, the question would be on which side of Bramwald to put the area. The only substantial clue in AiF (as far as I can tell) is that the AiF map shows a large winding river in the NE corner. I guess that kinda sorta fits either the Steelhead river or the Mogok river shown on the DA maps. Probably the Mogok works a little better since the Stealhead is more vertical.