I hope somebody knows an answer, although not everybody can be a wizzard, I guess this
is a bug in blender, but I just try it.
When I fill up a mesh somehow, with F, when you render it, it still seems that normals are pointing all ways. I could also try to save it as an object file, remesh it, and put it through
another remesher (Topological modeler e.g.), but I don’t think it wll keep the shape of
the mesh, if possible.
I don’t know what I must say but I guess its difficult.