After an eternity searching for the secret exit, I'm finally done!!! Great level overall, but there are a few things I'd like to mention:
-This jump is kinda annoying to do if you're big, if you could raise the ceiling by one tile it would be great.
-Timing with the Parakoopas here is a bit weird, they're usually out of the screen by the time they could pose a threat to the player. I might be misinterpreting something here though, I'm not sure.
-Those two Koopas areusually pushed out of the ledge by the rock here and end up doing nothing at all, I think you could remove them and it wouldn't change much, to be honest.
-Rock here could be moved up/left a bit, it can be really hard to avoid depending on when you jump since if you land on the edge of the platform it'll be really close to the player by the time you can react to it.
-Minor, but the Buzzy Beetle here falls off the cliff pretty much right after you see him.
-I found it a bit too easy to get locked out of the midway point, this part might play better if you remove the rock around here and leave only the Chuck. It's also really easy to run into the rock near the pipe, I recommend removing it.
-There's not enough indication of the pipe here at the moment in my opinion, I kinda happened to see it by luck and even then it took a fair amount of replays for me to randomly decide to wait around there long enough for it to appear. I think you could change the crystals' palettes here so they're slightly different from the regular ones, but not enough that it's obvious there's something there.
-Not sure if I like the current location of the secret exit door, normally having the secret exit path around halfway in isn't bad but considering the level is a bit more focused on exploration than the traditional Mario level the second trip is a bit tiring, specially since the player doesn't know which Yoshi Coin is replaced by the door at first. This might be impossible at this point considering how close to the deadline we are, but if you could move it to the first Yoshi Coin and expand the secret exit room itself a bit (which was pretty interesting, by the way) it would be nice.
Anyway, I really enjoyed the level overall. It's simple, both gameplay-wise and aesthetic-wise but it works really well. Most of the Yoshi Coin sublevels are interesting and the main sections are really well designed as well. It has a bit more nonlinearity than most levels due to all the sublevels you'll go through in order to get the secret exit but it's not overdone to the point it's confusing. Nice stuff as usual