There is definitely an audience for Holostars EN that would give like at least 5x the viewers they have in JP. I think the issue is
a) standard Japanese inability to accept that people outside of Japan might think differently
b) Failure of Holostars to achieve any decent numbers (tying into a)
c) Wading through a shitton of lazy 3rd worlder applications to find the right group of decent, appropriate idol-style content creators who aren't jumping on it because of trends/wanting to bone holos (I think this is the biggest issue based off how people respond to every single Hololive/HoloEn application)
d)
>>2272011 this kinda, there are a lot more male streamers, bulk of them do webcam streams for le funny reactions, you can't really do much with a male avatar whereas a female one is at least considered cute by the bulk male viewership of these streams.
I think a starsEN gen could work in spite of all mentioned up there, but the characters would probably need to start with some heavy fujopandering to take off and probably collab with the stars a lot to try and bump their numbers.