This calc is wrong let me explain why.
1. This is calc stacking. You don't have to use another calculation for it to be calc stacking. Quote: "
Hiding calculations is the practice of trying to avoid calculating a feat in order to be able to use the result in another calculation. In other words it is the practice of trying to fool people into not noticing that calc stacking is being used"
An example of calc stacking would be a character dodging a bullet from a short distance being ranked as "Supersonic". This counts for Mashle as in this case, instead of dodging a bullet he's hitting a Mach 7 ball (which is 10's of meters away from him) by moving a distance much shorter then the distance the Mach 7 ball has to travel meaning he's moving nowhere near Mach 7 and his reaction speed is no where near 0.00041649312s.
2. The calc forgets to take into account that sometimes Mash doesn't go the full distance of throwing the water out, he had to consistently return to his original position to give the illusion that he's standing still.
3. I personally counted 16 illusions of Mash so I'd like some proof of how the user got 31.