For me as a German the roles of Captain K and Jojos mom are clearly acting like the cliche American (posture, weapons (beginning), behaviour), which is very unfortunate.

The main reason why I still think the movie is still a good one relies on the conversations and the character development of Jojo and Elsa. Part of Jojos development is shown in Jojos conversations with Adolf, which is the only comedic effect in the movie, which Im fond of, because it shows Jojos childish behavior and him growing up.

I dont see why the plot would need any comedic effect, other than that (Adolf), specially since most of it is very shallow and some of it not even amusing.