Wowowow!! Thank you for taking the time to write such a exhaustive and kind review!! 
I really like the idea of having the platforms being one sided (jumping through the bottom)! I think that would definitely make it more user friendly after you finish drawing them! (I myself was blocked in after I drew a platform HAHA)
Oh yes, backtracking from the last level is indeed missing a way to go back! Thank you for pointing that out! c: Will update that part post-jam. ^ ㅡ^