Yes, it's not a bug! Devon's route in v0.12 update ends a bit earlier than Rune's. The opposite happens in upcoming (on itch.io, reelased on Patreon) v0.13 update, Devon's route ends a bit further into the day.
Unfortunately some of the saves won't work because we changed the definitions of a few transforms. Not functioning older saves is a common and frequent problem with RenPy, unfortunately. We're trying to avoid breaking saves, but it still happens sometimes.
Regarding Rune's showering illustration - the other variant is in SFW mode, you need to switch between the modes before the scene to get both variants.