According to Rabbi Ovadiah Yosef, non Jews cannot do complete Teshuva, instead their Teshuva only prevents negative judgement against them in
Furthermore, non Jews get punished for doing what they think is right without acknowledging the G-D of Israel and the Torah of Moses
[SOURCE: - Rabbi Yaron Reuven says that according to the Rambam a person goes to Gehinnom for doing a a righteous deed if he does not acknowledge that he is doing it because G-D told him to do it - and I assume that this should include the acknowledgement that G-D is the G-D of Torah revealed to Moses on Mt Sinai as Maimonides wrote in the Law of Kings ch. 8.11.]
In light of these, why would G-D create groups like Australian aborgines in periods of history when they had no chance of learning about the Torah? By doing, so wasn't G-D condemning them to Gehinnom without a test [as the culture and time period made access to the Torah a near impossibility], given that non Jews cannot reincarnate according to a question I read here (which cites a text called Minchas Yehuda by Rabbi Yehuda Hachayat... So we cannot say that such individuals are reincarnations of those that rejected the Torah, making their Teshuva difficult or impossible as a punishment)?
This would imply that certain non Jews were/are born in societies where knowing that righteousness for them consists of doing the seven commandments of Noah while knowing that G-D commanded them through the Torah of Moses is near impossible, and therefore Gehinnom for such individuals is guaranteed as they would follow their natural inclination to do good without knowing about the Torah.
This is seemingly against the infinite justice of G-D, and as for the reasoning that the nations are punished like that for the sin of having rejected or deviated from the Torah is that not punishing the descendants of the ones that rejected or introduced deviation, essentially against Rabbi Tovia Singer's claim that the innocent are not punished for the sins of the wicked?