I don't think you're a bad puzzle designer at all I think even that one that I had a gripe with was clever too just a little too slow. You've got a strong idea here if you don't have much background in puzzle design.
Oh, and also, specifically talking about that part you found frustrating... After I made level 4, I -somehow managed to- brake the entire platform-scaling mechanic, so I had to redesign all the puzzles from memory, so here we are. Yeah... sorry about that.
