For clarification:
My guess is this requires a custom action. This action would need to:
- determine the relevant Stereo Alignment Delay instance (e.g. which one is in the foreground - whatever's possible).
- take the slider values from JSFX. Sliders 1/2 are left/right delays (in ms - may be negative), and sliders 6/7 are left/right polarity switches (0 normal, 1 inverted). For this, it's probably fine to assume both channels are the same.
- move and optionally invert phase for all items currently selected
- reset the slider values (1/2/6/7) to 0 in the effect instance
I don't believe this should need any modification to the JSFX, but I'm happy to help if it does.