I am little confused as it should be quite clear how big the level is from the design you were given. (It was done by painting grid and gridlines are still visible) All jumps on the design should be possible with jump height defined in design, but I can't prove it...
Through little confusion could be caused as I actually uploaded 1 more version of the design, that had pure colored grid. (without images ...)
So the level is really big in your version, my design was much smaller. This most likely caused your confusion with jumps etc.
https://woprok.itch.io/project-a/devlog/238308/project-a-journal-entry-4 See version without icons, which is much better IMHO, than the one that you received.
Anyway implementing everything would probably take a lot more time.
So I take that doing last boss properly and some other parts can be quite time consuming.
And my goal was not to torture players, I was actually expecting it to be too easy :D
So, nice work trying :)