If Stored Power isn't on Musharna's analysis, then it shouldn't really be on Gardevoir's. And I think the Dual Screens set is worth keeping on site at least, because it's decently fast and gets the almost-unique and very helpful Healing Wish, which is a sufficient niche in my opinion. I used it a while ago to help out Gorebyss when it was so popular, and it's devestating giving a sweeper a second chance, perhaps even more so in this metagame with Zangoose. I'm less convinced about the weather supporter set, as most of the tiers weather sweepers are self-sustaining now, so I'd by happy to see it go.
I also think that Choice should still be the main set, as being a powerful and "fast" Psychic attacker straight off the bat is one of its selling points over Pokemon such as Musharna and Gothitelle. Although Calm Mind sets definitely have their merits in this metagame, they receive much more competition from Gothitelle now, so I'm happy with them remaining below Choice. Defensive Calm Mind in particular seems a little outclassed by Musharna, as Trace doesn't have a load of utility and Musharna has so much more physical bulk to throw around. This, combined with Gothitelle's presence in the tier means I'd probably never end up picking Gardevoir over something else for a Defensive Calm Mind set. Because of this, I think we should just keep an Offensive Calm Mind set, and make some minor alterations, perhaps into something like this?
name: Offensive Calm Mind
move 1: Calm Mind
move 2: Psychic
move 3: Focus Blast
move 4: Shadow Ball / Substitute
item: Life Orb / Leftovers
Ability: Trace
nature: Timid
evs: 4 HP / 252 SpA / 252 Spe
In summary: Choice / Offensive CM / SubWisp / Support / Dual Screens would be my preferred set order.