Tip: Layer 3 backgrounds and tides disappear when you hit a message box, so plan your level around that. For example, you can add a sublevel without layer 3 at the start/midpoint, and include your message there.
In short my hack is a bit stuffed. i moved a bit of my level to the right and then tested the level in snes9x and this happened: https://imgur.com/a/kWUwVsY and when i try and start a level it just gets stuck on mario start. Any help?