I forgot to say you should save in the cathedral. You can't escape the devroom unless you do something before hand. I think if you interact with the tree at this point it gives you a hint about needing to go outside the normal bounds of the dev room in more cryptic words. Play around with the teleportation orb in the new cathedral, you'll realise there's a place you haven't been before in this route. This room has something special that no other room has.
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Wait, I thought that the teleporter in the "modern" section always teleports you to the house of the guy that gifts you the gold dust in the "modern" section?
Oh no... did I do something wrong by getting the gold dust beforehand?
Edit: No, I didn't. It doesn't matter.
Update: WAIT! Is it the doorway that leads to the bedroom? (It is!)
Update 2: I completed the route!