This is a very bleak war film set in the Star Wars universe we know and love. That alone is going to cause problems for some people.
I would have liked it to be more bleak at times. Or at least consistent. In the sequence on Jedha, there is a small child crying in the street and Jyn hurries to rescue her. Then a moment later there is a guy doing martial arts comedy and a droid cracking jokes. These things do not go together.
While I agree with some of your assertions, this one I don’t quite see eye to eye on. To me, it just seemed like harmless wisecrack quips. It’s meant to loosen the tension, and I do believe that’s one of the best ways to do it. The bad way of doing so would be having a Gungan step in shit [cue laugh track]. Instead, some contrast is needed, even if the tone is serious. It’s not like that child was killed anyway (well obviously, way later we can assume that happened, sadly), so at that point in the film, the heroes are having their moment of triumph against the tyranny of those Storm Troopers. In other words, I never got the sense that our main cast of characters is ignorant to the gravity of the situation. So what, a child was crying, got saved, and was reunited with her mother(?); our minds were put into ease and open for some comedy finally after all that crazy action/drama.