Looking good and coming along nicely. As far as fixing any more issues, I personally would move on to your next piece and apply what you've learned to that. I feel it's not productive or beneficial to keep working on the same piece over and over again because everyone has different ideas on what would make a piece better. Take the suggestions you like and use them in your next artwork.
That being said, in whatever you do next. Remember that shadows start out darkest and most crisp at their point of origin, and fade off and dissipate(blur) the further they fall from that point. Also when laying down a shadow, pay attention to what kind of surface the shadow is falling on and how it would fall on that surface.
You did use atmospheric perspective on some parts this piece, but it was missing on others like the figure and parts of the city. Something at that distance would also be blurred slightly and not as crisp. Looking forward to seeing your next piece.