I'm liking it so far. Also on the bit from ages ago about Umber karstark borders imo there shouldn't be a clear border along a geologically feature like hills or a stream. Umbers have the largest land area under their control of pretty much every house but mostly because their borders are blurred.
The western border for the Umbers is the high valleys of the Northern Mountains, which they share with the Northern Mountain Clans. They also heard flocks of sheep and goats into the Lonely Hills, presumably shared with the Boltons. They'd also be around the northern shores of the long lake depending on the season.