This is an OK hack. Your level design is not bad. There are some issues that need to be fixed.
The Goal Post creates cutoff in the tree, just move it to the right. Easy fix.
The path looks cutoff the way it goes into the tree.
Cutoff rope and wrong corner tile. You used the bottom row of Lunar Magic which is not visible in game. Also, the Munchers look weird on top of the Bullet Shooters.
There is a better way to join up the ground. Use tiles 1E2 and 1E5.
Cutoff pipe and FOUR silent Bullet Bills.
I can see what you are trying to do here but the way it is done looks cutoff.
I know you gave a message about this but if you are going to do a P-Switch puzzle like that then provide the player with a reset door so that they can try again if they mess up.
Cutoff above and below the pipe. Just extend the floor to the left. For the top, insert the corner tile and add the ceiling. Note that the corner tile acts blank for some reason. Just set it to act like tile 130.
Ummm... wrong message. The Switch message uses the same text as in Message Block 1. Put this text in block 2 and insert the usual Switch Palace message in block 1. Also, make sure the Special Message is set for the right level. Go to Overworld -> "Change Special Message Levels..." The Yellow Switch here uses level 139 so change the Yellow Switch drop-down box to Level 139.
Yoshi Coin on boundary line. Press F2 in Lunar Magic and make sure that the Coin is not overlapping any of the green lines.
Cutoff. Either insert the top of the wood under the shooter or use the standard Bullet Shooter graphics.
What's the point of these 2 coins? If I collect them then Mario falls to his death. Remove these.
The Torpedo Ted skull blocks create cutoff in the ground. I know Nintendo did this in the original SMW but it just doesn't look good. Also, I found this underwater level a bit boring.
Really bad slowdown here.
Cutoff where the water meets the pipe.
The event above Mario creates cutoff in the cliff.
Slight cutoff where the lava meets the corner tile.
When I enter this pipe the game crashes. Did you use Podoboos (fireballs) or fish in the next room? If you did then ENABLE SPRITE BUOYANCY
otherwise the game will just crash.