Not sure what the adjustments are to Train/Train 2, but on the Switch with (I think) the original level pack I was able to pass both these levels by doing (spoilers):
- Create 'Wall is open'
- Create 'Rock is push and shut' (or 'Rock is push' + 'Rock is shut')
- Push rocks into the wall to the right of the 'Rock is push' area to access the vertical tunnel
- Grab any 'Is' and push across the map to make 'Flag is win'
I don't feel like that was the intended solution. But also it sure made me feel good about subverting whatever complicated thing the level was trying to make me do with the belts.