The situation has become a little confusing, so I have to be careful how I express the aspects. To answer your question, I hope, I build these models as scenery objects. I do not see any configuration that describes LibObject/SimObject, so that is a setting I may be missing. I have built the models as SimObjects, this requires different files and structure, like including a sim.cfg. In that configuration, the carla model appeared and was animated, however it flashed oddly, compared to building as a library object, in which it works fine.
So far, the only thing I know for sure, is that only the carla rig will animate, regardless the mesh it is skinned to. I have a feeling, that the "ModelBehaviors" section of my XML files, is ignored by the sim. The reason I draw this conclusion, is that it works in the original carla model. The model with the helicopter pilot skin is also a carla rig and that model works with the abbreviated XML you provided, Christian. I have not done the reverse test of using the abbreviated XML with the original carla, but I'm pretty confident it will work. No other models will work with either XML. I have 3 or 4 animated models I try with each build.
The fundamental difference, I believe, is that all animations that are not from the carla rig, come from Mixamo and those do not work for me. I think I'll have to explore other sources, before I can discover what prevents Mixamo. I know there is at least one video by Federico Pinotti about running Mixamo animations through Blender into MSFS, so there has to be some traction somewhere and that is another option, learn Blender also...
Attached is the latest version of the helicopter pilot with Mixamo animation saved to Max 2020, if you want to check it out.