Blender said it correctly.
There is no cook book method of autorotations.
Autorotational RPM setting, Weight of the aircraft, Altitude, Temperature, Wind, Airpseed, all effect the actual Rate of Descent and Ground speed....size of the area, location of the area, and barriers at the approach end of the area determine the kind of autorotation you will be making in order to land safely.
As an initial learning tool....a cook book approach does not hurt...but that is only to start out with. After that it becomes a finesse issue and that cannot be done by a cookbook.
Just a thought....if you have an actual engine failure...and you are doing an honest by God I gotta get this thing right autorotation....do you really care if you overspeed the main rotor during the final flare?
If the main rotor Autorotational Rotor speed has been set low...you probably cannot overspeed the rotor enough to hurt...if it is set too high...you might have to carry some collective all the way down...DO YOU KNOW WHAT YOUR AIRCRAFT'S SETTING IS NOW? Think about it?