There is no such thing as "international law" when it comes to national sovereignty. International law is not officially declared and enforced by anyone. Any definition of "international law" is irrelevant.
What matters is how international institutions behave with respect to the China-Taiwan issue. As I stated in my article, neither the UN nor USA recognize Taiwan as an independent state. Just about everyone accepts the One China principle.
USA has already taken a side...in the Three Communiques. But because USA is duplicitous, it continues to stir up shit in the China-Taiwan affair.