But they are also referred to as being north of Mistyvale (the county in which the Deepwell Inn is located), which Paarfi says is in Luatha, but Steve's Map shows is in Arylle:
Moreover, the only Collier Hills shown on Steve's Map is a small feature in the northwest portion of Arylle.
There appears to be a hilly region between Arylle and Southmoor that is not the Collier Hills:
These passages seemed at odds with one another, but when I asked Steve about it, he replied:
The most obvious elevated position in the southeast is Dzur Mountain, which is located due south of Arylle on Steve's Map, and is almost certainly the most prominent peak in the "not-quite-mountains" mentioned by Steve, which are located to the southwest of Arylle.
These latter hills appear to be mentioned again when Khaavren travels from Adrilankha to Bra-moor:
From
To
Go
Miles
Leagues
Time
Adrilankha
Bra-moor
Northeast
262
87
5 days and 4 hours
The references to "miles" in the above should probably be "leagues", since Bra-moor is over 250 miles from Adrilankha on Steve's Map.
I think that suggests that there is a row of hills that stretches from Dzur Mountain west and north to the area marked as the Collier Hills on Steve's Map.