Raven,
The reason for your confusion is your predisposition to think that the rpm is low because the engine failed. Remember that rpm drops when the demand for power is more than the power you have.
The demand for power is determined by many things, but collective setting is primary. As written, the rpm recovery procedure is telling you to demand less power (lower collective) and be sure you are at high throttle (increase throttle).
This procedure has nothing to do with autorotaion, in other words. The British term for the condition is overpitching, a really good way to say you are asking for more power than the engine can deliver, and so you are dragging the rotor down.
In a hover, this is a nice way to start an LTE event (I do not like that term, but it is with us). This means you are likely to hit the pedal stops during an overpitch because you have now demanded max power (max main torque means max tail torque to counter it) and at the same time you have limited the tail rotor thrust because the rpm is reduced (and rotor thrust is reduced by the square of the rpm).