I might be ignoring something crucial, but, as I see it, Chika simply is whatever she is to conform to a certain color of skin associated with the common gyaru. And then Selebus chose whatever ancestry he could to justify it being natural instead of the actual gyarus that tone their skin.
I don't recall any significant heritage trait from her background for it to matter... Not that I'd know either if someone didn't point it out to me, since I'm not familiar with either Filipinos or Latinos (that's a bunch of very different countries under a single name, which also doesn't make much sense).
Edit: for instance, Molly is very clearly Irish. It's a significant part of her character, it gets referenced all the time. Chika is just Chika, if she was Latina or whatever I don't see how that'd change anything in her character.