Before the end of ww2 people in Taiwan only spoke Taiwanese, Hakka and some indigenous languages.Of course some spoke Japanese as well. It was kmt that fled China to Taiwan and put a ban to speaking Taiwanese languages in schools. Kmt encouraged Taiwanese to learn traditional Chinese but as a Taiwanese I barely understand 1% of the meaning when the people from Hong Kong write in their way. By the way do you still live in Taiwan or you have been back in Japan ?