3 lie & 1 knows the way
The one who knows the way doesn't have to tell the truth.
You pull the red one because it tells the truth. Then you'll pull yellow because it was knew the way.
The part that was wrong is that they reset red saying "liars should stay together".
Yellow should have been put back
Ah, they pulled red because they spoke the truth, despite how little sense that makes when it comes to revealing yellow (which was revealed by blue in the hint). I see.
Well that makes very little sense, but at least there was
some logic ('pull all the levers with some "unique" property').
And yeah, I honestly thought it was meant that red should be put back
and blue and green gets pulled too (or if red was the liar then yellow would be only reset lever, and rgb would be pulled). Was surprised when they solved it by resetting the "liar" (which as you said wasn't a liar - but for arguments sake let's pretend it was), since I got snowed into having the liars be the 1's instead of 0's