I'd like to be able to change in which direction the the north pole of the celestial sphere is. In other words, what point the stars rotate around.

that is a good idea

i assume that would also change the plane the sun and moon are on? otherwise the physics is innacurate

Yes, although technically, the moon doesn't have to be on the same plane as the sun and planets. Earth's moon is ~5 degrees off. Moons that are close-in to their planets often have orbital planes more lined up with the planet's equator, not with the the solar system plane.

yeah, ofc in minecraft the moon is strictly opposite the sun, and changing that is too much of a change to vanilla for me to justify it