[Franek Grabowski]

I would say that any discussion about patterns without relevant German combat reports is a little bit pointless. There is a significant difference between overenthsiasm, not unusual in desperate dog fights, and deliberate fake claims.
In regard of the German victories, there was a lot of overclaim since the beginning of the war. It becomes apparent when one compares details of losses. The problem is, apart of lack of combat reports, that quite too often essential details like time & place are missing. Also exact circumstances of Allied losses are often not known. Thus matching of both contains a big grain of salt. I suppose that proper scrutiny of ETO/MTO aces would lead to quite dramatic conclusions.
Aside, shared kills and friendly fire are also to be considered. Still, without combat reports nothing can be said for sure.