I'm probably missing something here but my All Speed's have the 3 Flex Adj bolts in the rear, well 2 bolts in the lower holes and a plastic cover in the top hole.
When the 2 lower aluminium bolts are removed you can see the threaded inserts/nuts they screw into but removing the top plastic cover just reveals a blind plastic hole, removing the boot liner confirms that it is only the bottom 2 that are usable for adjustment.
All the literature I've found reads that all 3 should be threaded!
Taken from the Rossi sites pdf on the boot.
"The shell/cuff connection gives the wearer the option of adjusting the boot’s flex by changing the position of the screws. UNISEX’s models: 3 screws WOMEN’s model: 2 screws ALLSPEED 2 SCREWS DOWN 2 SCREWS TOP 1 SCREW TOP 130 130 120 110 120 120 110 100 110 110 100 90 100 100 90 NOT RECOMMANDED 90 90 80 NOT RECOMMANDED 80 80 70 NOT RECOMMANDED"
Any thought gratefully received.