Yes, you can precalc, and then you need very precise actuators to move the mirror to that precalced position. You also need precise surveying of the ground sit

Yes, you can precalc, and then you need very precise actuators to move the mirror to that precalced position. You also need precise surveying of the ground site to know its geometry. The precise actuators and surverying are expensive. Their approach is using cheap actuators in a closed-loop system where a computer vision controller (using the four cameras on top of the tower) moves the mirrors until it gets it right. Cheap actuator slip and lag is terrible, but with the feedback of the closed-loop, it's doable. This is an approach that's now allowing hobbyists to build cheaper motorised telescopes, robot arms and so on.