I am not sure why you are importing the model via the GG importer because you seem to already have everything you need for it, IE N,S and D Maps, the exported model, the fpe file and a bmp.
I have not used Cinema 4D but it seems to me that you have everything you need without importing.
Have you just tried opening this file in GG without importing. All you should need to do is change the .dbo to .x in the fpe file and it should work from that.
If that doesn't work have you tested the size of your model, is it really small in GG.
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