Isn't the earth's eccentricity incredibly low? (To the point that human-noticeability or non-precision-machinability are out of the question?)

That's not to say I have any comment on the accuracy of ellipse calculation. Keplerian mechanics are beyond me. But I did see a the gear-ratio calculation repo linked: https://github.com/amandaghassaei/tellurion-orrery/tree/main...

It seems angular positional error after 100 years of simulation was the optimization goal.