So, IF the airport in France has coverage, that would be an easy way to check the tracks for compliance...
If you mean coverage by one of the enthusiast ADS-B networks, that wouldn't really help much as
AFAIK they don't record the NUC_P parameter that accompanies the ADS-B airborne position transmission, so there is no way of knowing how accurate the track is.
The best outcome would be if GPS-originated data could be downloaded from the aircraft itself. That would allow the authorities' tracks to be verified.
So back to the OP ...