Madam Web. The premise of your perception being un-stuck in time and the ramifications that has for your psyche is really cool. What’s not cool is hiring bad writers and nepo baby actresses to portray that story

Nobody would be able to understand me because English has diverged so far from 12th century English that it’s a different language. Also I’d be in north America where nobody had even seen a white person. Additionally, I’m 20 ft above the ground right now in a building that didn’t exist back then. Finally, I’d be rightfully blamed for bringing plague to the native tribes of the area and likely killed.

Assuming those hurdles were all cleared: I’m a mechanical engineer. So, I’d tell the natives where iron ore, coal, and oil was buried and how to extract and refine it. Tell them how to make gunpowder. Speed run making steam engines and lathes. Get north american natives armed, industrialized, and organized against the external European threat.