A solution perhaps could be to create a general plugi,n import in a fisrt time ?
Import of :
-Model
-Animations
-UVMap and Diffuse
-2nd UVmap if used (for lightmapping for example)
Its the minimal thing we need.
If the plugin can do that we can do the rest of the job :In the engine editor add the normal map (specular or another) we need and and shaders to the model.

Well importing all maps (normal, specular,glow etc...)from FBX : don't work same way for 3DSMAX or Blender export.