1. Mechanically, why are Schemer and Temperamental both in the game? They are very similar, but schemer seems like a much more negative trait to have.
Mostly because it helps assigning traits to people. So many leaders, not enough negative traits to go around. But I agree that Temperamental should probably be buffed.
2. For the next version, I'd highly recommend overhauling China's city names. If we're looking at overall history, it should be Chang'an, Luoyang, then Beijing. Nanjing is the 4th Great Ancient Capital, but I think it'd be better for South China? This is a problem since Civ IV came out.
Already way ahead of you here. For the next version, every leader will have an accurate city list reflecting the particular political setup at his/her age. China in particular benefited a lot from this, as their almost 3000 year timespan between leaders means that those lists almost don't overlap. BTW, the work is not over yet for all civs, so someone with your attention to detail could help a lot if you want to contribute to city list compilation.
3. For Japan, I don't think Meiji and Hirohito should be leaders. Japanese Emperors have always been figureheads without real power, like the British monarchy today. I would replace them with Okubo Toshimichi and Hideki Tojo, respectively.
Because they both identify well with particular eras in Japan that are well-reflected in Civ terms. While they were figureheads indeed (though that is somewhat debatable in case of Meiji), they were
leaders of Japan. There are many cases in history where the actual driving force behind the monarchs were great statesmen defining their policies, but in most cases I included the nominal leader, the symbol behind whom the actual policies might have been carried out by other people. The only exception that comes to mind is Churchill, but his wartime powers made him a virtual dictator and he actually can be argued to be not only the
de facto, but also the symbolic leader of wartime England.
4. Should the Austronesian civ be renamed Indonesia? I know Indonesia is super large and has been several unique civilizations for millennia, but the austronesians are such a massive and diverse group it feels off to classify all of them as 1 civilization. All the leaders are from modern-day Indonesia, and many incorporated groups could be civs in their own right, and many are (Polynesia in Dawn of Civilization comes to mind).
Were I inclined to add more civs, I'd definitely split off Malaysia and Philippines. But I am not, so this won't happen. Also, you are not 100% factually correct here, Parameswara isn't from Indonesia. And while modern unit lineup is mostly Indonesian-based, earlier units are a mixed bunch.
Philosophically speaking, we are rather lucky as a mod team that modern world led to creation of "cultural union countries" in most of the world, including entities such as India and Indonesia that never existed before to such extent, as it makes that so much easier to provide modern-day content for them. But they should not be equated (at least blindly) with historical civilizations occupying roughly the same territories.
5. The civilopedia refers to Nelson Mandela in the present tense; I don't think it's been updated since his death in 2013.
Goes to show you how old the mod is. He was still very much alive when we put him in.