When a female biologist visits a canadian mountain to search for bears, she discovers a small village that never had contact with modern civilization since the villagers came from europe in the 17th century, and she has to fight for her life when the mayor thinks she might be a witch and they should burn her.

Female is a poor description for an MC. For starters, you wouldn’t describe the MC as male if he were a man. Secondly, ‘female’ is perfectly generic (it describes half the population in the world) and therefore means nothing in a logline. Best you describe an MC with their major flaw and let the pronoun inform the reader as to the gender especially seeing as it’s relevant in this case.

The most important thing a logline should do is describe a goal, so what does she do after being accused of witchcraft?

Last note is to shorten it, here is an example:
After a biologist stumbles across an isolated village of settlers’ descendants, she is accused of witchcraft by the mayor and must educate the people to save her own life.