My boss gave me the cold shoulder, demoted, and my colleagues around me alienated me.

Obviously, you have the wrong company! Originally, you didn't know Korean, but you stayed in a Korean company, which was already very unfavorable for your work. It happened that you offended another person who knew Korean. She is full of mistakes, but you can't reflect them upward. However, she can say the square is round and the white is black by virtue of her dialogue ability, but you can't do anything about it! If it were me, I would fire my boss and resign!

This kind of company, with chaotic management and low efficiency, will die sooner or later. Of course, I will also gently write a letter to the boss's boss, telling him the reason for his resignation and telling him that "this kind of company has no future"! That's it! That's enough! Take a step back!