Indonesia is a birthright citizenship country, extending Indonesian citizenship only to individuals with an Indonesian father, and to ALL children born in Indonesia of an Indonesian father. Moreover, in the 1960s Indonesia didn’t recognize dual citizenship. At Maya’s birth her mother (and father) would have had to make a decision: whether to use Maya’s mother to claim US citizenship for the daughter. I suspect that they did so. Otherwise Maya would have had to go through a complete adult naturalization process, which I don’t think she needed to do.
Whether Indonesia recognized dual citizenship is irrevelent. Maya could have been both Indonesian AND American without the other country knowing about it. Indonesian laws do not affect American policy, and American laws don’t affect Indonesian policy. Even if Indonesian law forced her to renounce her American citizenship, she still would be a U.S. citizen.