With a round Earth, we are able to perfectly predict the time of sunrise, sunset and the movement of the stars and planets.

We've been able to do that for millennia (at least). It has nothing to do with the believed shape of the earth. It has to do with watching the lights in the sky, recording them, and noticing the cyclical pattern. The shape of the world isn't involved, as much as you may want it to be.

With a round Earth, we are able to perfectly predict the time of sunrise, sunset and the movement of the stars and planets.

We've been able to do that for millennia, it has nothing to do with the believed shape of the earth. It has to do with watching the lights in the sky, recording them, and noticing the cyclical pattern. The shape of the world isn't involved, as much as you may want it to be.