I just checked and looks like you mixed up something. The room with "green was never one of our colors" has red, blue and green doors. The orb lets you know that the "true" vision doesn't discern neither red or green. So, in the end, they would see 2 gray and 1 blue door. Since there's no way to determine which of them may be green that you can't use, the only option left is the blue door.
As for the progress, the puzzle is tricky. In the example above, you picked the blue door, but it looks like you ended up in the orb room. This means you made a mistake before. This trick is in so saving after each door won't help you that much.
Yes, the final room with that plate is not a test room. You made a mistake somewhere before, so all the doors will lead you to the orb room.