When using GenerateMeshes4D.GenerateCompound (and presumably also the corresponding 5D function), if the group includes elements that do not preserve orientation, the faces generated by those group elements will have their normals incorrectly reversed. The code does take into account the possibility of such an error, and uses a call of Mesh4DBuilder.FlipNormals to try to correct for it, but that function doesn't do the right thing in this context. The normals directly produced by applying the inverse transpose of the transformation are already correct, the only thing that would need to be fixed is flipping the winding order, whereas FlipNormals changes both.
When using GenerateMeshes4D.GenerateCompound (and presumably also the corresponding 5D function), if the group includes elements that do not preserve orientation, the faces generated by those group elements will have their normals incorrectly reversed. The code does take into account the possibility of such an error, and uses a call of Mesh4DBuilder.FlipNormals to try to correct for it, but that function doesn't do the right thing in this context. The normals directly produced by applying the inverse transpose of the transformation are already correct, the only thing that would need to be fixed is flipping the winding order, whereas FlipNormals changes both.