Except if the reflectors are shaped for wide area illumination, then their focal distance is probably nowhere near the distance from the satellites to the earth’s surface. So I don’t think is any “single point” to be had.

Heck, I haven’t done the math or anything but I bet even if you did instead use parabolic reflectors that were tuned to focus at the earth’s surface, it would still be very difficult to keep them aimed at a specific point for long enough to achieve significant heating. I wouldn’t be surprised if it’s difficult to achieve an increase in heating that’s close to, say, the heating difference from standing outside at noon as opposed to 5PM. Which then doesn’t do much because you couldn’t effectively use a reflector at noon, anyway. You’d want a lens instead. Or some sort of complicated Newtonian telescope type contraption.