I found quite a lot of errors!
This bonus area in Rose Plateau 1 - A First Begins! plays grassland music. It doesn't fit in caves!
Rose Plateau 2 - Beetles Swoopers also has grassland music.
Don't use the bottom row.
In Rose Plateau 3 - Troopa's Shroom, there are 2 powerup blocks here.
In the same level, what's the purpose of this bonus room? There's nothing here.
This level also has only 4 Yoshi coins.
Switch Palace - Yellow Block is a blatant edit of the original Green Switch Palace.
The message is also empty besides the yellow blocks being there.
W1 Ghost House - Brick Hallway plays athletic music.
In Rose Plateau 4 - Platform Cliffs, these dotted yellow blocks were inserted with Map16. Use the Add Objects Windows to add these blocks instead.
In the same level, if I break these turn blocks, I'm stuck.
It's the same empty bonus room from Rose Plateau 3.
Rose Plateau 5 - Mushroom Waters has no enemies at all!
Don't use a goal post or goal orb in a level with layer 3! The tide disappears when the course clear scorecard appears.
World #1 Castle - Boom Boom Tower plays the switch palace music.
Iggy? I was going to battle with Boom Boom, not you!
Even though you said that you've finished the first level of world 2, it has no name, and entering it takes me to an endless bonus game.
Also your levels has too many multi-coin blocks.