You do know that these "killers" also saved another millions of Indonesians from Communist coup right? So stop talking about bringing this one and that one to justice because the so called justice depends on the one who wrote it. To some people, these "killers" are heroes, but to some other people they might be assholes. For example, Mao might be an asshole for ROC, but he is a god-like to CCP China. It is the same for those "killers", Indonesia might become another Cambodian Khmer Rouge if Communist coup succeeded, so to some people, these "killers" saved them from communists hardliners.
Do you know that the number of the "Angkatan ke-5 or the 5th Forces" of the PKI (Indonesian Communist Party) in 1960's exceeded the number of Indonesian armed forces? Who knows what would happen to non communist Indonesians if the republican forces did not take any actions to prevent the PKI from taking the control of the government. And the victims of the communist purge in 1960's weren't only Chinese, all people that came from many different ethnic, who appeared to be communists, were also purged.
What wrong with this movie is that the maker only focus on victims who were chinese, rather than taking the whole picture of the massacre. Making it looks like a massacre that only targeted Chinese.