Hi.
I do not think Keller was anywere near Leningrad, as he probably took off from St.Omer-Wizernes on a fighter-bomber sortie against England. The 10.(Jabo)/JG 54 was the 10.(Jabo)/J.G.26 after renaming, and went on to become part of S.K.G.10 in April 1943 (so it only existed for about 2 months).
Loss record here:
http://www.ahs.no/ref_db/lw_loss_pub...?lossid=111674
The aircraft lost by JG 54 on 18.06.43 was the following according to my list:
http://www.ahs.no/ref_db/lw_loss_pub...?lossid=111677
http://www.ahs.no/ref_db/lw_loss_pub...?lossid=111678
http://www.ahs.no/ref_db/lw_loss_pub...?lossid=111679
None of these seems to be directly linked to an aerial combat.
Regards,
Andreas