"At that time my brothers [Taiwanese people], who were beyond doubt [acting in the capacity of] Japanese person[s], fought for the motherland [Japan]."
"Japan and Taiwan were the same country then. Being the same country, it's of course not true that Taiwan was involved in the war of resistance against Japan."The United Daily News did it's best to suggest Lee was suggesting he is Japanese, today and forever. China Times too. Meanwhile the government run CNA parroted Chinese claims that Lee was destroying Taiwan-China relations and, in another article, used the familiar "scholar" quote headline to claim that Lee can't tell the truth from fiction and has unclear logic. (You can read more of this particular scholar's comments here.).
Meanwhile, Tsai Ing-wen said Lee was speaking from his historical perspective, while Mayor Ko pointed out that all parties in the kerfuffle were speaking truthfully from their perspectives. Ko's comments showed a lot of maturity I think.
My view is that Lee correctly sees he has much great political capital and influence in Japan than in Taiwan, so he is using that capital to try and tug at Japanese heart strings and bring Japan to express greater support for Taiwan's continued independence. Meanwhile he figures that in Taiwan the worst thing that will happen is his comments will force the KMT to make itself look even more China-oriented, which can only help the green camp.