It would be really good if FME's GeometryValidator could validate composite solids.

Currently it does not detect disjont or intersecting members.

Here is what FME should be able to validate: http://en.wiki.quality.sig3d.org/index.php/Modeling_Guide_for_3D_Objects_-_Part_1:_Basics_(Rules_for_Validating_GML_Geometries_in_CityGML)#gml:CompositeSolid

For 3D validation workflow this is a critical test which currently can not easily be performed.