Your top screenshots shows how the fields are assigned from KOMK/KOMP structures. You can open KOMK in transaction SE11 and then in the definition you'll see that the field KUNNR has type KUNAG = Sold-to. It's the same in VBAK table - Sold-to field is called KUNNR, not KUNAG.
Kindly close the discussion if your question has been answered.
