For example will German children grow up ignorant of the fact that the swatika (not allowed to be used in Germany today) was emblazoned on WW2 aircraft? (black belt...)

Of course, the swastika is allowed to be shown (the Horst Wessel song allowed to be sung) in films, or theater plays about the Nazi time. It would be allowed in history lessons in school. It is also allowed to use the swastika in a context which makes clear that it is used as part of criticism of Nazi thinking.

So for instance when neo-Nazis reported their opponents to the police for using a crossed-out swastika (or, in another cartoon, a swastika being thrown into a garbage bin) as a symbol against neo-Nazis, they (the neo-Nazis) had no success.

Forbidden are some songs and symbols only when used for endorsing the thinking historically related to them.

Wolfgang