As i noticed recently there is something called InstancedStaticMeshComponent in UE and also Revit has a familytype system, seems like they have similarities. UE uses instanced mesh for performance increase so while importing from revit familytypes should come as InstancedStaticMeshComponent by default. This will allow whole scene to perform better. Inorder to execute this operation every same family type in revit will come UE as one InstancedStaticMeshComponent. Best example for this is doors, when importing doors to scene they are generally exact same door , only a few type but a same type will have a lot of clone in a big project.