I think I have a solution for the shadow situation.
Try to modify the DXF-DWG Translator settings as seen in the image:
In the "Drafting Fills" field type "SHADOWS".
This way you specify that all Drafting Fills should be placed onto a newly generated SHADOWS Layer in the created DWG file.
This will affect Shadow Fills because in ARCHICAD they are in the "Drafting Fills" category.
Of course, this will affect all Drafting Fills in the Section, including the Elevation Marker's Fills, but I hope that is not a big problem.
I suggest one more modification: change the "Create Layers according to" field to "ARCHICAD Layers" from the default "Layer extended by Pen Number", because this latter option will create a lot more layers.
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