>> There is not this problem with other progs like modo c4d ...?

> No, it's not a problem with other rendering programs - both Modo and Cinema4D for example will load vertex normals from a file and then be able to use those vertex normals for shading when rendering.

Do Modo and C4D have problems when a mesh is edited (or at other times)? In other words, are there times when Modo or C4D recalculate vertex normals and you end up with a bad model once again?