Grats on completing the challenge Vaniilo, it's a real marathon.

One thing that jumps out at me right away is how a lot of the center boxes have almost the same proportions and orientation, like 187 to 203. You'll learn a lot more trying all different kinds of sizes and angles than trying to perfect that one box over and over again.

Your line confidence is fairly well done, though I do see a few times here and there where you retraced a line. Try not to overdo it, as retracing the line makes it bolder and more obvious that you made a mistake.

Your angles vary but you seem to have a good grasp on it, seeing that you got several perfect convergences. Just remember to be aware that there's two different kinds of foreshortening (dramatic and shallow), and to practice both.

I like the small notes you did on each page, you clearly knew the most important parts that you needed to work on and fixed them accordingly. I think with enough time and practice, you can easily iron out all the small kinks in your boxes. Keep going!