Where in academia are HEA fellowships valued?
(Nearly) all UK universities want to signal that they take teaching seriously, both for student recruitment and for the TEF, for the obvious financial reasons. 

For this reason new faculty are typically required to undergo training to reach a qualification that either leads to an HEA fellowship or is equivalent to it. Thus HEA fellowships are the national standard for teaching. Typically new faculty are exempt from these training courses if they have an HEA fellowship.

Anecdotally various people within my own institution have said that the push to get more faculty accredited with HEA fellowships was important for an improvement in our TEF ranking. There continues to be a big push to get more existing faculty to do the paperwork for HEA fellowship, although I do not believe it is a requirement (or even mentioned as desirable) for job applications for the majority of posts.