Haha, you kind of made me smile because this game was meant to be quite obscure and I did not expect you to go that far in an hour to search all endings. I'm happy you enjoyed so far.
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Spoiler (True Endings):
Actually you almost have two true endings there. Within that moment while doing the quiz and how many notes you have. If you completed all the notes, that leads you to either two true endings depending on the quiz.
You may need to fail the quiz from here and have all notes. This will lead to the second ending. Not having the notes leads to the neutral ending of course despite failing or winning the quiz.