Grief. Let me get this right.
A Russian, in an American Experimental aeroplane, flying around Europe, on an FAA licence.
Because that aeroplane is sub-ICAO and from outside the ECAC area, that is subject to individual overflight permissions for each country being overflown, and because it's experimental there is no standardised build standard under which EASA can ramp check it.
What a bag of worms! I'm just glad it's not mine to solve. Looks like a fun aeroplane however - although you can't help wonder about the deeper reasons why it was never certified by the FAA.
G