RNG based run, first I tried declaring directly and adding a lot of non infamy war goals, but Qing never backed down. So first declare a war against a small nation and raise some conscripts to boost your army power projection. After the war fires declare for transfer Joseon, your mobilized army should be big enough to give you a 10% chance of Qing backing down.

Qing backed down on April 12, I thought the achievement would pop up if I unpaused, it did not