My hot take
I wouldn’t have a problem with Sakura being in the group if she was over 18. Her dancing is decent not amazing but I think it meets the minimum requirements. Her singing is not great but at least she kinda has some breath control.
The real issue with the group (other than Sakura’s age) is that they have three members with weak vocals. Emily can kinda get away with it because she at least has the excuse of being the main dancer and Sakura to play devils advocate you can at least argue age and lack of training, but Lexie….
I went back and watched the final performances, Lexie was out of breath with shakey vocals throughout. She’s had at least around 3 years of training and can’t cope with a 2.25 min song…. That’s rough. It looks especially bad when you compare her to Rinka who in a matter of weeks produced a stronger vocal performance (and arguably sharper dancing imo).
I think maybe part of her issue is she’s trying to do this breathy ‘sexy-baby’ type voice and it’s just coming across as kids bop.