You cannot change your game mode and then bring back your progress.
I used to unlock what I wanted in normal mode, and then I'd flip to hard for a challenge with encounters.
Since I cannot do this anymore, the game has become very unappealing to me. Unless this is fixed/reworked I think I'll be cancelling my patreon, because even though the save word was annoying, I could still edit the events and play how I wanted.