We are familiar with Tabor but only from an athlete perspective. I am just not sure what the standards are for admission, or the academic support is, for a kid who isn’t going to be a varsity all the time player.
I think the idea to find out about learning centers is an excellent one. I know Brooks has one - that might be a good fit. They have some amazing teachers but are definitely not as intense as some of the other MA schools (maybe too far away from your daughter?).
Taft, ehh, I am not sure that fits what you describe. I know both teachers and students and it was fairly intense.
Also, since this might not be our last pandemic, you might want to check out how schools are handling things. For example, Concord Academy, all virtual, that would kill me as a parent.