I could probably explain it better — having now solved the level in the puzzlescript editor in what I hope is the intended way I think I'm right in stating that the right-hand side of the level is supposed to 'lock' the passage between left and right until you the disrupt the rightmost bouncers and cause the round to change the cycle of the vertical bouncer.
1) In your original version of the level, it would have been inconsistently solvable. Something was creating a situation where the right-hand area could unlock itself without player intervention, which meant if the player did nothing at all and waited, they could ignore the round being kept in place by the two bouncers, and just proceed with solving the left-hand side of the level. However, if you did try to solve the right-hand side in the intended way, sometimes the unlocking mechanism would go wrong and make the level unsolvable.
2) In your revised version of the level, the level became unsolvable. While the bouncers did what they were supposed to initially and remained indefinitely in a simple loop, when the player disrupted that loop the mechanism would no longer unlock, as the vertical bouncer was ultimately unable to dispose of or get past the two horizontal bouncers:
https://gfycat.com/blackunselfishamericanshorthair
3) I noticed that the original Kye version of the level appeared to have three timer blocks in the right hand section and so added those to the level in case they were there to fix some sort of collision issue. The change did allow me to solve the level by following the intended strategy, but it ended up recreating the issue in part 1, where the mechanism will always unlock itself if you do nothing (sped up footage below):
https://gfycat.com/ecstaticcheapflatfish
It may also be the case that there are situations in the layout above where the intended solution causes the unlocking procedure to go wrong and makes the level unsolvable.
Hope that's helpful :)