Regarding House Hawick/Cox of Saltpans the two houses are confusing, however, what if Cox was just a knight in service while the lord was away at war? Also , the town needs to be relocated further west, as does Quiet Isle. The current locations are not accurate enough in our map.
If it's from the Lands of Ice and Fire, The World of Ice and Fire or A Song of Ice and Fire books themselves are canonical (all three books are officially produced with either GRRM's personal involvement or his guidance).
Tbh if we really feel like we’re going to do anything to adapt to that map, we should move Perryn and Chambers, nothing else until such time as someone wants to do the cox/Hawick lands. If we cut deeper into the riverlands as that map does in the north we’d be risking scraping projects. There’s plenty of room for houses around the gods eye that ice currently filled with extinct Harrenhal ones
Considering there's been sentient and intelligent habitation for a minimum of ten thousand years, surely they've mapped accurately by now? Also, remember Aegon the Conqueror did travel on Balaerion and map as they flew the entire nation, and they had flown over other territories as well.
Meh i believe he means borders, there was a constant struggle and dispute over medieval borders whether it be from a farmers quarrel with his neighbour or a war over a couple of km. Thus meaning in the eyes of whoever got a cartographer to make the map their version of the territory may be different than that of another. In the case of chambers, it’s cut off from the Vale geographically so the people there may even feel more a kin to the river people than those of the Vale due to similar lifestyle caused by their surroundings. However to the Arryns it grants access to the Kings road allowing major economic expansion for the Vale to the rest of Westeros. Or is simply just bragging rights of having large territory.