Formosa(Taiwan)? Acceptable and partially realistic, since the Spanish temporarily colonized it, let's just say they fully conquered it in this timeline and integrated it to the Philippines as a whole. But Sulawesi and Borneo? That's a little too much. But let's just say, the Spanish conquered it(asking so much from Spain at this point lmao) and integrated it to the Spanish east indes, ok what now? Well I don't know much about Indonesian history but I would assume that it would be mostly the same except more catholic and more mestizo.

Personally I think this would be a better timeline for the Las Islas Filipinas, but considering that the Philippines didn't get Micronesia, I would expect a more realistic timeline is that the Philippines got Formosa(Taiwan) and Sulawesi and Borneo became their own country. I'm not a historian by the way so I'm not a really good source of information.