Responses
If you remember the mangas name do tell
She meant this?
Red haired mc who used to be called genius kid, but ended up miserable, and blond haired ML = The Stereotypical Life of a Reincarnated Lady(〜￣△￣)〜
http://www.mangago.zone/read-manga/the_stereotypical_life_of_a_reincarnated_lady/?lf1Z
Yep that’s the one
For all you complaining about the MC not acting her “mental age”, think about this... if you were to go around acting your real age in a fairly young body, how do you think people in a Middle Age time period react to that?
Given most people during that time were plagued by superstition, not very well. In this case I will grant you they are a bit more modern, but the issue still stands... There is actually a webcomic (I forget the name of it, but it’s the one with the Red haired FL and the blonde hair ML), where she tried to act her age and such, and honestly it did nothing for her except make her more miserable; so there.
You have to remember that in a lot of these comics the FL is trying to survive a situation, and so they can’t just whip out their modern know how all Willy-nilly. And in some cases the FL does (eventually) use there past knowledge (i.e. Doctor Elise). But again, in these cases they had to be careful how they went about it, and often had to establish some ground work before they could proceed.