Is it intended that this barding uses the Desert Catfish as a primary component and can't be refined for additional stats?
As far as I can tell, refining doesn't do squat. It was never "fixed" before launch as promised. But yeah you can't refine food mats.
Refining was fixed for everything but hides. However the mount gear should be taking the pattern, rather than the rare as the primary component, so they can't turn out refined anyways as you can not refine the patterns. On my end the recipe does show correctly with the pattern as the primary, but if you are seeing differently that would be a bug.
I maybe wrong but even in VoV, refining the mats did not make any difference to barding of potent. It was the same stats even with refined mats.
Yep, because refining only does something if the primary component is a rare, and in VoV the pattern was the primary component. Refining the build components provides no benefits.
As Zhevally said, refining build components does not provide any benefits, and mount equipment is not intended to benefit from refining.
Actually it goes back even further. the Void-etch stuff from RoS worked the same way, among other examples.