I contacted Axel Urbanke and he replied with the following information:
- He has not seen and does not know anything about any wartime diaries.
- Karl Borris worked as a Taxi Driver in the DDR after the war - apparently his wartime career prevented him from doing anything else.
- Borris had children and they are (apparently) alive, but we don't know more than that, or how to contact them.
I can tell you that Borris shot down my father's Spitfire (RCAF 416 Squadron) over Belgium on February 3, 1943 - his 23rd victory. My father managed to bail out, and hid in a barn with the help of a local farmer in the village of Wylder. He was discovered by occupying forces and spent the rest of the war in Stalag Luft 3.