I really don't know how to complete the "plunder china" quest

Even if I colonize Taiwan, I'm not within plundering distance of the northernmost provinces.

Allying with okinawa also does not fix the problem in any way with the mission "wakou piracy"

And not even the casus belli of war against the world is useless since it is not at valid distances, it would be necessary to take lands from Korea (fighting against China) to be able to complete the mission, which is quite nonsense... xD

Any recommendations on how to do it or is it a bug that you should correct?