I'd say it's pretty obscure outside Japan. It's only had two titles localized, ten years apart, and it would be generous to say the first one "underperformed". Honestly I'm not sure how you can argue it isn't obscure outside Japan.
Within Japan it's definitely another story, there it's not obscure, but I wouldn't hold out hope for a series with as little western recognition as this one.
And it's nowhere near as prevalent as Dragon Quest is in the west (or the east), before someone makes that comparison.
Niche in the West sure, but when has that stopped other series before?
Fire Emblem never had a game released overseas before Melee, but the characters were still included regardless and it helped jumpstart the series coming overseas starting with the 7th game, Lucas is in Smash despite Mother 3 not being released here and likely won't be released here for a long time, and both of Bayonetta's games underperformed (This is taking into account the first game selling over 1m copies) and she still made it in as the alleged Ballot winner nonetheless.
And considering Sakura Wars has gotten a cafe, a dedicated store, stage shows, multiple TV series, radio dramas, a theatrical film, a **** ton of crossover appearances, and is still influential on games to this day like Persona, Mass Effect, and even modern Fire Emblem itself, I'd say the impact the series has had is pretty notable, hell it was even one of the first SEGA IPs to come to Nintendo systems and had a Game Boy Color model because of it's sheer popularity.
My thought process is that Smash could be used as a tool to help the series overseas as it's worked for many other franchises, SEGA seems to be really pushing the series right now, correct? Something like Smash I imagine which has a huge install base and loads of other beloved gaming franchises would absolutely help boost it into the limelight here, while it would probably be generally accepted by Japanese audiences. I think as long as they market her well and she's fun to play that's what matters most.
