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.

I have tested Bornholm X with the new P3D 2.1 patch. The problem with building textures on trees are now resolved. Unfortunately, my custom-made approach- and runway edge lights still does not work (both are of the type "BGL_lights" and they are apparently still incompatible with P3D). I may need to redesign the lights in Bornholm X. Other sceneries effected by this problem: Sonderborg X, Sindal, Saeby, Herning and Randers.