It’s telling that they didn’t include Asha in this lineup, considering that her movie is literally called “Wish.” Of course the movie bombed at the BO, but it’s clear that Disney doesn’t have high hopes for a turnaround for this IP on D+ (FWIW I just watched the movie and I thought it was pretty bad).
Asha would have been a much more natural fit for this theme than Mirabel, who isn’t really strongly associated with the “wishing” concept in any way. Tiana wishes on a star, Aladdin is granted 3 wishes, Cinderella sings “A Dream is a Wish Your Heart Makes,” but there’s nothing particularly “wishy” about Encanto (sure, the characters have desires, but that’s true of anyone). Mirabel is obviously here only due to her popularity, in contrast to Asha’s lack thereof.