I think that FSX models a sort of mesh influence on the stations, rendering their signals to be disregarded by the flight sim gauges in the cockpit under certain conditions .
But you are right, that 200 or 220 nm max. limit is hard coded it seems.

The only real trouble I have with that are the ADFs in my eyes, as they are way to limited in range in the sim while reports shows huge (useable) ranges in the rw on some.