By my count, of the 20 exposed squares on the dish, the central 8 are right on, as are 6 of the outer 12. The final 6 have too much curvature and don't contribute more than about 1/4 of their light to the center spot.
In the best case, I think I could get 1000 suns from this dish,
using a target of about 6 cm^2. I doubt I could rely on more than
500x, though, on a regular basis. I'm just guessing at this point.
Tracking on a partly cloudy day was a little erratic -- the dish wants to "run home" to the parked position a lot. An improved algorithm might make a world of difference, even with no changes to the sun-finding scope.