I notice with other games that at that point is, as you said, difficult to generate a good image that represents what you want. But the great thing is that with so many characters you don´t need to add more and more stages each update for each one of them.
Cool that Zoe and Mia are getting more love. Zoe is already having good events but poor Mia is lacking. I usually replay the game each update and I find her always being 2-3 stages below the others. So looking forward what you have planned for both of them