Actually Sailfish is what makes you have to move the extruder carriage around by hand. What Flashforge is using is an older procedure and what my older Qidi did before the Sailfish upgrade. Evidently it has been decided by those that write Sailfish that the manual way is better. I heat the build plate up then go into the leveling operation.
I start in the front center adjusting the two front adjustments so the paper barely touches the nozzle tips. I then move to the center rear and adjust that one the same way. While doing this you can check that both nozzles are the same. I then goto left center, right center and finally center. Hopefully by then everything is level. I'm sure there are other ways to do it but as long as the plate is level when done it doesn't matter.