>>717889872
If you want an actual non-tribalfag answer, BA's target audience is simply more niche. The schoolgirl aspect being front and centre was always going to filter 90% of normies in the west. Also the gameplay is really simple outside of raids since the focus is on the story, so there's nothing for streamers to latch onto because watching someone reading text off of a screen probably wouldn't be that interesting. Also like >>717890198 said the people that would have played it already were via emulators, so there was never any big spike, the existing playerbase just moved over to Steam.
Compare that to Uma - which while is also set in a school setting, is focused on horse-racing which is a lot more palatable for normies (yeah there's absolutely a double standard there but the point is that normies perceive it to be more acceptable). Gameplay is a lot more involved, especially since rougelikes/lites have been trending, making it more interesting for people seeing brief clips of it in whatever social media pages they use. The characters being based off of real-life horses also creates more point of discussion for people that want to learn about Japanese horses. It only recently launching in the west also helps, since there's the FOTM syndrome normies tend to catch for new releases, time will tell if they move on to the next trend or if they're here to stay.
>t. Plays and enjoys both games