Well for Mai, Chinese accounts fits the description of kingdom which is centered around Mindoro Island. There are also archaeological evidence on trades between Mindoro and Chinese.
I am assuming your POD is Yongle Emperor ruling China timeframe based on your original post(1402-1424AD).
Yes, China and Sulu have good relations at the time Sultanate of Sulu existed which is around 1457AD+. At the time of Yongle, this type of relation did not exist since Sultanate of Sulu did not exist yet.
Assuming if Brunei did threatened Chinese Trade in Luzon, China will probably directly invade Brunei than invade Luzon or Sulu. POD will be around Sultan Bolkiah's time around 1485AD+. However, Yongle has already died by this time.
In OTL, Kingdom Tondo still existed even after Brunei invaded Tondo. Rather than be its original form of an Indianized/Hindu/Buddhist kingdom, under Brunei, Kingdom of Tondo became Muslim. The only time Kingdom of Tondo stop existing was when the Spanish arrived. So, if you want Kingdom of Tondo to continue to exist, POD must be vs Spain which is around 1570AD+.