Glad that you like it!
But I'm going to have to disappoint you. Playing a level on hard mode after beating it on casual mode kinda defeats the purpose though. Hard mode is easy if you are levelled up to the old level cap and have all items in the dungeon already. For example the first dungeon, you would start at level 10 after completing it on casual, while the level cap is 8. You wouldn't get the shortcut, but it wouldn't matter since you already have another shortcut. The only thing different are the cursed rags, though you already have rags and can just use the console to get that item.
I would suggest just keeping two saves, one where you play on casual mode, and then one where you play the dungeons on hard mode, and then swap between the two.
Another reason is that I also want to keep hard mode exclusive since playing all dungeons in hard mode will unlock the true final boss battle.