Okay I was writing up a more extensive post on why certain heroes don't have cosmetics yet, but it basically boils down to Valve Time. You
can make items for heroes that haven't been released for cosmetics, but in all likelihood you're going to be wasting time (could be a little, could be a
lot) doing so. So there isn't much of a point in working on such things when you could be making sets/items for heroes that are prepped for them with a much more reliable turnaround (as little as a week to get into the store from the workshop.)
If not listed on
this page, don't expect anything soon for a hero.
Specifically regarding Luna - she was broken down in the game files and in the importer for a time, but has since been removed from the latter. The whole deal with the updated mount (being in on test, then being out after many people disliked it/preferred tea towel cat) likely slowed everything down with her.
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Also the sound mix on Dream League today has been way off. Not sure how best to describe it, but
something feels muffled in comparison to everything else. I think the commentary level might be way too high.