Oof. I recall reading this raw some time ago, and thinking that while it was a good douj, there's no way I could ever bring myself to TL it (for length or content, take your pick).
Well yes but also no. I remember my idol hell years, following LLS! idols- from concerts to interviews, radios, etc. And if i remembered aright, they were all at least in their early twenties when they started. These girls' werent very 'talented' when they began too. And some fans were griping about their subpar singing. But the bulk of the fans defended them, pointing out that you arent really enjoying their performances for their talent, it's more about watching them have fun, etc. Though i guess it's a gray area since theyre technically VAs too, idk.
For the record, no, Shuka was definitely in her teens when she started - lied about her age on her initial application, even, iirc, to get in. I think the oldest was... Rikako? in her very early 20s.