My understanding of it is that everything you're doing "on-lead" during the seven games is setting the foundation for doing the same activities at liberty. So while it seems very exaggerated on-lead and while first learning, the end result is a subtle communication between horse and person.
The way I was taught PNH backing with the rope wiggling, we DO use body language as well...facial expression, body stance, etc. I was also taught to hold my finger up while going through the backing phases (phases as necessary) which makes a "no-no" type gesture. This ends up being the cue for backing at liberty (the no-no gesture).
The same applies for the motion used to collect the line back up to retrieve your horse. Using that same motion at liberty is the cue for the horse to come back in to you.