Unlikely, but the regional authority (e.g., US FCC) can fine the radio "operator" for radiating out of band signals in excess of the regulation's emissions mask at band edges. Operating at full power in a "channel" (frequency range) outside of the FCC defined band would give the operator no defense - it's a knowing act if firmware's region settings are altered. All it takes is for anyone to file a formal complaint with the FCC. They will follow up on the complaint. But not likely ever go looking for illegally operated radios.
I thought that the current revised rules (which will be mandatory for all devices starting this summer, currently only mandatory for NEW devices being submitted for review) required the manufacturer to ensure that an end-user cannot easily modify the region for which the device is designed, and failure to comply would mean you wouldn't receive the FCC certification required for selling your product in the US.