When has sovereignty been "established" in Taiwan?
If you believe that it has by popular vote then you have to accept that sovereignty has been established in Crimea & Donbass by popular vote also given that: (a) China owns Taiwan according to China & the UN (b) Ukraine owns both Crimea and Donbas according to the Ukraine & the UN.
If its good for the goose, mate, its good for the gander...eh mate?