Well, only thing I could find is that Germany has a prohibition on the use of swastikas. This could give problems when being put on German based servers, indeed. On the other hand, you could give a twist to the argument that your swastika is being used for historical purposes, as games such as RTCW and W:ET do carry an amount of historical weight. If you argue that your swastika is a part of depicting historic scenes or such more, perhaps it might be considered legit.
As for other servers, based in other countries, there seems to be no problem. Some time ago, Germany lobbied for a general prohibition on the use of swastikas in the European Union, but the idea was countered by the Hindu community for whom the symbol is actually a deeply religious one.
Lastly, I will add that the symbols you use on your aircraft, in my opinion, doesn’t symbolize the real swastika, rather some other military symbol especially used to mark the German aircraft at that time.