The hiragana ち is not an error. The mixed kana writing system was carefully designed by Nakasone Seizen. The choice of hiragana and katakana does reflect phonemic differences. The phonemic transcription is designed specifically for the Okinawa Nakijin hōgen jiten (1983) and not for other purposes. It only represents the dialect of Yonamine, Nakijin. Other dialects require their own schemes. After all, there is no such thing as a Kunigami word in the real world.

Misleading readers into believing unstandardized things as a standard constitutes original research. What  is doing is even worse. He is promoting weird schemes that cannot be found outside Wikipedia.