The people who founded it had relations with Sri Vijaya, in fact some of the people of Sri Vijaya took refuge in the Kingdom of Tondo.
Before the Spanish invaded the Philippines the languages in the plains(some of the survivors of which are Kapampangan and Ibanag) resembled Javanese...so any successful rebellion before the Spanish resettled the plains would result in a Luzon speaking a Javanese like language.
That is if the PoD is right after the Spanish resettled assuming that Spain conquers Philippines like OTL. Also, this is under the assumption that everything assumes like OTL.
But the assumption/PoD is either China conquers Philippines pre 1500, which in turns make Philippines more like Japan, Chinese culture which will transform separately as different society much like Japan.
Or if it is later than 1500 AD, Chinese conquest would still remain closer to OTL. I severely doubt any successful rebellions by Filipinos between 1500-1800 AD. Spain was just too powerful around that time and Philippines was too disunited. Of course all your assumptions again are that we come to OTL which contradicts OP, which is making Philippines Sinicized.
OTL, We all know Philippine Culture pre hispanic is much closer to cultures in Indonesia. However, this is ATL with the assumption of Chinese conquest.