From what I understand the firmware (in the ObserverIP) distinguishes US equipment (Ambient) from other labelled version by inspecting the frequency of the wireless sensor packages, which are 915 MHz in the US and 433 MHz elsewhere. The ObserverIP itself is not actually different, it is the sensor wireless.
So, in your scenario, in order for things to function, the firmware would have to discover, or you would have to configure 433MHz, and that would then "disable" uploads to ambientweather.net.