The two "piggy-back" pneumatics you show aren't what I supposed - they're most likely secondary valve operating pneumatics.
Are you sure the box on the right is the wind-motor governor? If so the pneumatic probably operates the valve to speed up the motor on fast forward and rewind, and the one on the left hand box may be the action cut-off (silencer).
If the left hand box is the bass expression regulator, and the right hand box the treble expression regualtor (and the wind-motor governor is elsewhere), the pneumatics either operate the accenting secondary valves, or action cut-off valves.
You need to find which tube makes each operate, and which pallet valve or tracker-bar hole they go to. Then we can probably deduce their function!
![Smile :-)](./images/smilies/icon_e_smile.gif)
Patrick