Hi,
Schertl might have led the 6.
Staffel temporarily, because there weren't too many successful officers in the unit in February 1944. Otto Schulz passed away recently (28 July 2013). I established contact with him in 2011-2012, but by then his memory of the war years had faded. He was one of the more important members of the unit and, as you say, hasn't received too much attention.
Cheers,
Andrew A.
Air War Publications -
www.airwarpublications.com