If they are funding them secretly then they are not doing a great job.
Whatever happens a full-scale attack and annexation of Arakan is required. Savage land is totally isolated and China cannot afford to go against BD as it has no "allies" bar Barmans and Pakistan. Neither of these countries can help China much. Myanmar has destroyed China's reputation and Pakistan is a fiscal drain on China.
The prize for BD is too huge to turn down - giving Rohingyas their land back and a region that is rich in agricultural, forestry and hydroelectric resources that can fuel BD growth.