Thanks a lot for the advice! I made this level around launch when I got this game, and I remember I was pretty unhappy about the floating platforms issue. I planned to come back to it later, when I got the tool to create tracks, but I somehow forgot and just uploaded it without thinking too much about it.
-the first hidden block you mentioned is indeed kinda arsehole-ish, now that you mention it
I'm thinking about an arrow, or a coin to place there
-I never thought the Koopas would pose such a problem! I assumed most people would be more slow and cautious while climbing the ladder
-I'm also thinking about relocating the checkpoint flag to the top of the ladder section
Anyway, it's great to get this kind of input, especially when you don't really have people around you who can play-test your levels.
(BTW, I just cleared your "I've been here before" level and I thought it was brilliant! Will check out the other ones as well.)