Tools to do Semantic Anotation on 3d CAD Models
I would like to update that I was able to perform annotation on the 3d models by using following tools

Semantic Segmentation Editor
Blender
FreeCAD

Blender and FreeCAD are easy to use, but needs some postprocessing to get the annotations right especially on point cloud data, whereas Semantic Segmentation Editor can be used to directly annotate the point cloud but that stuff is not easy.