Unlike the DomainName function for a Feature, you'll have to provide the code to get back anything for FeatureSets
I am trying to solve the same problem. Did you figure anything out?
I can get it to return the domain code and am thinking I might have to set up a series of if statements to change the code to the description. It wouldn't be pretty but I am not getting any more ideas on it.
Any update on this issue other than hardcode the domain name?