Jan,
Thank you so much considering Jean-Bernard´s feelings seriously. I highly appreciate that and feel very pleased to notice people do not and should not forget about the devastating iniquity back in WW II.
Being a citizen of just that country that brought so much pain and inhumanity to face the world isn´t an easy task to live with.
My thoughts and prayers still are with those having suffered so badly and given their lives to end the sick regime that once ruled germany and tried to spread uncalled for.
For this, it is quiet hard for me to tell anything about the badge included.
I do not like it either since I comprehend what initial feelings evolved with Jean-Bernard and he may not be the only one.
Regarding the painting one has to admit, that my color refernce refers to the assignment when delivered by the ship yard.
Not sure what time period and place you chose for your model though.
I am pretty sure the Kriegsmarine used whatever paint they could get a hand on late in the war and far from the homeland. This is supported by the fact that logistics and money pretty much suffered as well.
The captured midget subs in a row on Wikipedia might just reflect various conditions by paying due to the time frame of commissioning.
I am not convinced the color shades are visual wise only related to a wet/dry surface.
For this, I may stress that to me your painting looks very nice and throughly done. It is just sort of heavily weathered but others milage may vary.
A shot of a medium gray filter might do the trick.
Also, maybe do a snap shot at daylight, if you do not mind the suggestion.
Jean-Bernard is right about the diorama layout.
The single worker at the midget sub is not related to the scene. If you want to keep the configuration I suggest to give that person some tools so it makes sense what he is doing there. A hammer and a small table with other tools might be a good starting point.
However, a very impressive and clean built and my honest respect you give the audience a chance to provide input.