I just played through all the levels in your set, the ideas are good but there are a lot of problems. I hope you tested the levels yourself because half of these levels are impossible.
Here are the changes that must happen:
03: Give the platforms a second or two when they go down so the ball can get on.
06: You need to have some sort of hints for the invisible parts like Hard 15 or TDF 06; otherwise it's impossible.
07: Not enough time to get all coins, time needs to be extended to at least 30 seconds. Also wrong edge texture used, should be edge-purple-check.
(To do that, go to Tools, Find & Replace, then type edge2-purple-check for Find and edge-purple-check for Replace. Then press Apply)
08: Very broken level. First it doesn't even have target_deathmatch, making the level impossible; even if there was, the goal count is 50 when there is only 38 coins. And I think there's something wrong the first and third goal platforms because they go too low. Lastly the edge texture should be edge2-brown.
10: The clocks are impossible to get and the time is too short. The thwomp clips through the platform, and the platform goes too fast to collect the yellow coins. Also, there is no poof-violet.
11: Replace red textures with turf-green-check too look better. I don't like that you have to get all coins either.
12: Also could use better textures
13 Replace coin textures to coin-green-dark. Also don't like that you have to get all coins.
15: Time is too short. Also should be city environment.
16: The level doesn't function well, the second jump is hard to do.
17: Time is too short, needs more clocks or extend the time.
19: The side textures are visible n the arrows.
20: There are a lot of thing wrong with this level, the jumps are hard and the platform is impossible. Also the last row should have the same background.
I: Ball should not start on the goal. Also teleporter above blue coins should be a detail brush.
II: Not possible
III: The other switches doesn't stop the platform.
IV: Good, but should be in city environment.
V: Also good, but too short and easy.