I am glad for manga like this to give the unvoiced idols a lot of love given how limited their role in the actual game is for obvious reasons. This is admittedly systematic of Cinderella Girls being really early in the gacha lifespan so things were a bit different back then alongside the fact the VA's have to do far more than simply record lines for iMAS, but given Starlight Stage unlike the original game doesn't really have unvoiced for main events it really is side works like this that allow for these lesser known characters to take center stage. Luckily Million Live!, SideM, and Shiny Colors doesn't have this problem so those series have better rotation, but hopefully we'll continue to get more idols voiced as time goes on and hopefully that'll include Mai and Chika so the full unit can be complete one day.