Honestly, I'm not exactly a fan of the voice actresses they chose. Asahi is close enough, but I feel like Yae sounds a little too normal and sweet and Yuna's voice should be a bit higher. Of course, that's just me. I'd definitely have preferred one of the other lineups.
Shirahi appears way later in the manga, so I wonder if this announcement indicates some anime original scenes or some sort of flashback in the beginning, where she has some lines.