Hello Vlado,
You’ve got a mail :), from fabien at le-truc dot ch (ready for download in 20minutes)
The only parameter in the VRayColor2Bump is height. (2.40.03)
I made a simplest version of this scene, 2 objects, 2 lights (VRayLights 1 dome full with VRayHDRI map, and 1 plane), and only 3 VRayMtl
I try more thinks :
Dome Only: OK
Dome + Plane : Problem
Maybe it is a Spec/Reflection issue, or a size issue, parts are very small (6mm)
Maybe with a particular angle at that size, we’ve got a problem.
As I say, I’m not a specialist, just a regular user 
Best regards.