I will cut to the chase here and say that the only reason for not calling it "Taiwan Province" is if you are (1) an American Imperialist, (2) a Japanese Imperialist, or (3) a running dog of one or both types of imperialist.
It doesn't matter to me what "normal people" call Taiwan Province because the vast majority of what you consider normal people are completely ignorant of the topic, the history, and the legal political situation.
You don't get a say in what terminology I choose to use. Your insistence on prescribing what exact terminology I can and cannot use dances on the border of pointless liberal semantic nitpicking and petty fascist power play.
No amount of semantic maneuvering on your part will change the fact that Taiwan, Province of China is recognized by international law and the vast majority of the countries of the world as being a part of China. No amount of quibbling over words or pidgeom holing me into your imaginary categories will change the fact that the vast majority of countries and international law recognizes the People's Republic of China as the sole legitimate governmemt of China.