Hi fopix3d,
friday the 13th should be an unlucky day, istn't it? But that's not true at all, but not for me!
I got the problem with the bogies solved, the orientations (rotations) of them where wrong in the blender file. Now the bogies and wheels work correctly and move. And if I get my train coupled (it is still just defined as a wagon) to a Loco, I can drive around.
Btw, thanks a lot for sending me your coupling blueprint, I took your settings out of it. Does the definition of 'Type' in that blueprint not have any relevance ingame and is free to set? Any exampe blueprint i look at has different definitions and names in it. And it seems you took your own definition as well.
But these couplings still keep driving me crazy... As long as my train is uncoupled, the geometry of the coupling is displayed well, but by the time I couple it to another unit some weird things brake loose.
As long as it is uncoupled, everything is fine:

But by the time it is coupled, the coupling disappears:

But it does it only between my train and the standard loco.
If I couple my train together one part of the train displays both variations of the coupling (coupled and uncoupled) while the other shows it just correctly:

But it's the same model, just the same one...
Btw: I placed all the different coupling types at 0.0.0 in blender for export and changed the position in the .xml file with that little nice tool from UKTrainSim (RwCoupling) and did the following settings:

The pathes of the coupling blueprints somehow doesn't get be processed the right way in that tool, maybe the path of my files is too long for it. So I fixed it manually and it works fine. But never the less the whole thing just doesn`n work the right way...