Having built a map with that system before, I have the following observations:
The sizes can get a little wonky: in particular vast regions take up a huge amount of space.
Shape is not specified: I like to make larger versions of a size category long and skinny (length is specified distance), while short ones are fat. One thing you'll notice is that small and large areas give the same number all the time.
Direction is not specified. Nor is which area is considered 'adjacent'. When faced with a decision I actually rolled to see which area would be considered adjacent. You can also use 'quantum positioning' to ensure certain shapes, like mountain ranges, are kept: if its another mountain, continue the chain. If not, stick it off to the side.
I
built a tool to make rolling up these maps easier.
Ultimately, the map builder does NOT work without human intervention, and its stronger for that fact.