Okay, thanks to this review I found out that the behavior of that little guy is completely broken, which made that particular part very finicky and difficult as well as generally throwing off the design of a lot of the rooms. For reference, this is what they're supposed to do:
This happens because of an issue with Godot that only happens in exported builds, which is why it got through testing. I got permission from Falcon to upload a second page with a fix, you can play that here if want. The save file should carry over without issues.