So I'm a bit uncertain if this is a bug or not, as this is caused by extracting the .rpa files.
To explain: Most games, when I try them out, I extract all .rpa files and bring back the .rpy files from the .rpyc files if they exclude the .rpy files. I usually do this as a security measure so I can fix potential small bugs myself I frequently encounter in renpy games with relative ease, or at minimum, at least better understand why I may be coming across an error (some of them are beyond my ability to fix). This is as opposed to being stuck only reporting to creator or waiting around for someone else to come up with a bugfix. Although I do admit I also occasionally make small tweaks here and there on games as well.
So in this game, when I did this, I encountered an issue. This issue "only" happens if you extract the .rpa and get the .rpy files from the .rpyc files. One file in particular, at "game/1000_base_game/game/characters/isabelle/q_isabelle_piano.rpy" has an indentation error at line 24. The problem however seems to be at line 19, reading,
. If you bring "parallel:" (after "transform:" on the same line), on line 19, down 1 line to line 20, and correctly indent it, it fixes the issue.
As long as it's kept in original format you get the game as, you won't encounter this issue. But in case anyone else extracts files like I do and comes across this issue, that is how you fix it. Felt like I should share that just in case it can be useful to others.
Oh, in case this issue is changed in future versions, this at least applies to the version I'm using, which is version 1.27 of the game.