The ecu would need flashed to Europe in the country of origin for the ecu to recognize the gages.
But, as mentioned above, the U.S bike doesn't have an ignition immobilizer, so that will not work.
I went through this with a gsxr750 years ago, as the Busa format defaults to U.S settings...but the gsxr's in that version of Ecu Editor defaulted to EU...the ecu bricked in that bike(and was flashed in the bike, not on the bench)...but worked fine in another just like it.
(I ate that one, bought him a new ecu, and still have the old one, and it works in other bikes, and can also be flashed to use in a 600)
None of the ecu gurus had an explanation outside of the obvious, the 2 aren't compatable.
You can have the ecu flashed to Any country code, and it will work fine.
It's just the Immobilizer in the harness that prevents it from working properly.