It's not terrible, it's certainly impressive that they achieved that level of isolation with holes in it. Windows designed for high sound isolation will have STC ratings in the 40-48ish range. An STC increase of 10 equates to half as much sound passing through (as a human perceives it anyway).

As for the air passage, I'm curious about the real world flow numbers.

Just an off the cuff guess: it seems like the core principle is based on resonant cavities which I think would result in higher air pressure in the cavity than inside or outside the window. In a setup like that with calm ambient conditions I wouldn't think much air would actually pass through the panels, the higher pressure in the cavity would act as a bit of a wall. In windy conditions I would imagine much more air would pass through, but I bet there would be a corresponding decrease in sound isolation as air blasting through the cavity wouldn't be able to dissipate as much energy.