It has always been the case in the Ori games and, to my knowledge, most other games, that any kind of manipulation of the game state prior to the start of the run is not allowed. I don't really see a good reason for allowing it, when all it would do is just make the grind significantly more annoying due to the need to set up the game state prior to every attempt.

Regarding the Wellspring Trial specific rule, the main reason it's not allowed is because even the game doesn't consider the runs that climb the right wall to be valid, and it hides those runs from the public in-game leaderboard.

I don't think anyone has properly tested it, but I wouldn't be surprised if it doesn't work. There are already a number of glitches that don't work on the Switch version.