Where does T'Challas sister learn science from

Agreed. The reason that Oxford and Cambridge and Harvard and Yale are such highly-respected universities is because they have Professors who are the among the top scholars within their fields from all over the world. Since Wakanda doesn't allow foreigners into their country, Wakanda's universities wouldn't have any top Professors and thus would be low-rated schools and nowhere as good as top universities like Oxford and Cambridge and Harvard and Yale.

Wakanda's universities are probably no better than the average community college in America. That would explain why no one in Wakanda is smart enough to come up with a peaceful way to choose a leader without any violence and bloodshed and mortal combat when most of the rest of the world has already done so. Because isolationism has made Wakandan 1 of the dumbest nations in the world.