So essentially they blamed her for a natural epidemic and then stole her research after making her take the fall for an act of god that she herself was researching a cure for. How lovely best yet she can't really get revenge since it's been 800 years
I would disagree with this assumption, mainly on how the stealing her research. as it appears that her explanation of how miasma works is rejected by everyone in the classroom, including the teacher.
What instead appears to have happened is simply that she tried to come with new ways of using magic that everyone could do so including people with little magic and that was easier to do that even children could learn it, plus a research to deal with miasma, but the people in the past rejected her teachings, and instead branded her as essentially a witch. And the people kind of came up with an alternative way to deal with miasma, though it remains to be seen if that's really the case or something else to be explained yet.
Which may or may not involve some "evil prideful" noble plot not wanting the commoners or weaklings to learn magic, as that tends to be the case in these type of WN stories.