> Could you produce a report for the school's administration of each professor's confused/understood ratio?

That would probably make professors (especially non-tenured professors) either terrified of making use of the app, or terrified of tackling complicated subject matter. Even if administrator's announce they aren't going to use the data to decide salary or tenure issues, good luck getting the professors to believe it.

Feedback that helps professors improve is great. Yet another administrative metric that warps people's behaviors, not so much.