So the US is English?
There may be other arguments that Taiwan is Chinese, but I haven't really given you my thoughts on those (hypothetical) arguments.
China and Taiwan can share a history, but that doesn't entitle them to reconciling their differences. Much like the other commenters brought up, establishing Taiwanese independence is obviously the smartest path from here. China has had their feelings hurt for almost a century over Taiwan. Entire generations of humans have lived and died in the time Taiwan has enjoyed sovereignty. China knows it's time to let go, but they can't look weak or suffer the same fate as Russia. Continuing to threaten Taiwan is just part of their political-industrial complex, nothing more.