When I think about what this story is basically, it's about an intern teacher disguising herself as a high schooler to spent time and flirt with an actual high schooler. The age difference is fine, but she's still a teacher, worse, HIS teacher. And the way she's lying makes it so much worse. This behavior is disgusting.

I understand the idea of the story, but there are ways to not make it unethical and immoral. For example, not making her pretend to be a high schooler on purpose. It starts by a misunderstanding, but there could have been more occurrences instead of MC deciding she's going to literally cosplay her high-school self to deceive a boy. It could have been funny if she kept being mistaken for a student by other students and teachers, getting tasks forced on her, etc, for the comedy aspect. And the romance could have happened outside the school, with the characters seeing each other at the convenience store, and really spending time together after she stops teaching him.

Also, outside of all ethical and moral considerations, she really acts stupidly, puts her career (and entire life actually, she could (and should) have risked criminal charges) in danger and then we're supposed to think she's a martyr when she "takes responsibility" by forcing an apology on everyone. A total trainwreck.