[[ This is shorthanded ]]
The issue with FBX and collada.. is that terminologies and methods are interpretive when implementing the SDKs into functionalities for 3rd party toolsets. 'meaning the DCC tools not AUtodesk made, game engines, SP..etc etc...(Also, the FBX-SDK version /time of plugin creation may matter too)
Hence plugins/importers/exporters/)readers/writers) get wonked or are featureset specific.. and perhaps need to be adjusted either at plugin-code-level or perhaps in scene of the DCC tool.
The one image clearly shows issues with indexing issues of mirror'd meshes..perhaps the mesh was not collapsed to a polygonal model prior to export..(and then, what version FBX(sdk) exporter?) >.I simply can't know without the files and programs to se..and that's not going to happen.
This type of bug is easily solved by the import/export writers of the DCC tools ..or even perhaps included as flagged approaches/checks during SP2s' file importing.
No need to be upset, this is an easy thing to solve..they simply needed to know it is a problem that exists.
