Are you sure the normals are incorrect? In City Viewer models are exported without normals so they should be derived from vertices coordinates in the obvious way by an importing application and I don't see what can go wrong there.
i figured out the issue, .json from the Fantasy Village to here then .obj out creates geo where vertices are not welded. Once I did a weld, i could fix all the normals, even without a proper "floor" on the buildings.
