Bingo. Mapping isn’t code run on the PB, which is also why @pixie 's recent post about the URL for the map returns text, not the actual map. (Right @wizard ? Is there a way to get the normalized (or not) map data right now? )
I agree, at this point, combining the sensor(s) in real time with transform/rotate is your best approach to changing the map. Heck, now I have an idea for a sound reactive pattern… On the pile of todos.