I would recommend having the team do some interviews with power users of this functions. @ball, @ayeung, and @arbaughj are pretty active on these forums, but I hope you can also find more non-US-based people.
I’m not an authority, but my major initial reaction is that I would prefer for reference terms to be logically grouped underneath the source they belong to. I.e. there’s no “browse all reference terms” but rather you click into SNOMED-CT and then you’re browsing the reference terms in the SNOMED source. And then you have an Add button that lets you add a SNOMED term.
(Conceivably one might want to search across all reference terms.)
A few of my comments in this post refer to Reference Terms: Concept Dictionary OWA 1.0.0-beta released! (Actually, reading that I didn’t say much about reference terms)