Hi @turrican welcome in the plugincafe community.
I moved your topic in the correct category and assigned tags, see (How to Post Questions) Please do it for your next topics.
Regarding your question, yes it's possible to do it in python. however, I suggest you contact maxon support to report the initial bug regarding the FBX importer.
Now you have to keep in mind here we don't code for you but help you to achieve what you want.
So the steps in python for doing it are:
Loops over each material. Retrieves their name. Create a Bitmap Shader and assign it to the correct channel of the material (normal).To loop over each material, keep in mind that material in Cinema 4D is BaseMaterial which is a child class of GeListNode so to loop over all material use
# Retrieve the first material of the current document mat = c4d.documents.GetActiveDocument().GetFirstMaterial() # loop over each material while mat is not None: # Do the things for each mat mat = mat.GetNext()To create a bitmap shader (c4d.Xbitmap) and assign a texture to it find an example in shader_create_bitmap_r13.py.
To know the ID of the normal channel, just drop and drop it into the console, see Python Console - Drag and Drop.
Cheers,
Maxime.