I guess what you are saying is that the graph plots of the onset of buffet define the corner, but that after onset there is a further unplotted area of 'forgiveness' in which recovery can be effected without severe upset?
I'm not sure where you're getting that, but no. You seem to be implying that once buffet starts, progressing farther into that region the effects go away. Not the case. Generally as the low or high speed effects begin, any further decay or increase in airspeed will make the effects more pronounced. The exception will be aircraft utilizing artificial means to create the effects, such as a shaker; the aircraft itself may not actually be experiencing any effects at this stage, but rather the shaker may be serving as a warning several knots (or a degree of AoA) in advance of the forthcoming stall.
One may not experience any actually buffeting or stall at the airspeed operating limits, or one may. Where mach or stall effects are encountered, however, you're not going to see them as a brief occurrence that goes away as one progresses beyond the buffet boundaries.