As the product page says, Bornholm X is for FSX SP2/Acceleration.
It works just fine in Prepar3D v2 also (and the installer even has an Prepar3D install option), but there are some minor issues because of the backward compatibility issues and bugs in Prepar3D v2 (which hopefully will be resolved in the upcoming patch). I will announce the scenery for Prepar3D v2, once these issues are resolved.