Autorotating in a R22 is all about technique, yes if not done correctly, the Rrpm will decay to dangerously low numbers: I've seen 78% with students; but it will always be recoverable if the basics are followed: SPEED = LIFE up to the FLARE, thereafter RRPM = LIFE to touch down. It simply means that if you maintain 65kts or higher up to the flare, you can basically recover from any low Rrpm situation and still be able to do a safe full on auto or landing in a real engine failure situation.
Just a small reminder; remember Rrpm is a function of ROD; the lower the ROD the lower the Rrpm; we need to fall to be able to autorotate!!!