keeping the same
teacher around for several years is in the best interest of the school

Institutions do not have unified 'interests'. Senior officials at a University could care less about the duration of particular white faces adorning the campus. The FAO department needs to renew visas for both new and returning teachers. Department heads want foreign teachers that do not cause 'problems' and are anxious to replace those that dare to question the quality of the facilities and academic programs.

If you consider what is in the "best interest" of students, the termination of unqualified uncaring teachers is always in the students' best interest.

In China, there are wonderful FTs living in dungeons and there are drunken loons living in lovely apartments. Amenities do not impact teaching ability.

Even if your data was able to screen out responses from unqualified deachers, providing recruiters with a 'quality survey' to improve education is equivalent to working with pimps to poll working girls about women's rights.