I mentioned this in Star Palace's status a while ago, but here's a list of the voice synth related crowdfunding campaigns that have happened in the last year (going back to summer 2020, and it's entirely possible I forgot some):
- Zunko's various CF campaigns - all succeeded
- Tsuina-chan's Synth V campaign - success
- Seika's Synth V campaign - success, though it was close
- Adachi Rei's A.I.VOICE campaign - success, though it was also close
- Miku Expo 2021 - success
- 1st Place's concert campaign - definitely will not hit the goal, but it's flexible funding so they'll keep all that was raised
- Solaris's Synth V campaign - success, though it was getting close
- Rosa's CeVIO AI campaign (and even if this succeeds, will there be more campaigns to try and fund the other banks they wanted to make, like the English talk bank and the Synth V languages? Iirc this current campaign is only for the Japanese talk bank, and stretch goals past the initial goal to fund this haven't even been announced) - TBA, but it's not looking good
And this doesn't even include miscellaneous crowdfunds that have happened but aren't exactly voice synth related (i.e the Kotonohas were pushing a crowdfunding campaign to succeed due to their involvement being a stretch goal, and it did hit that goal in the end).
All that, and there are at least two more crowdfunding campaigns that we know of that will begin as well: Tange Kotoe's A.I.VOICE campaign, and the campaign for the two twin CeVIO AI banks (assuming this one ever... actually starts, considering the person in charge of this product has apparently been quite the controversial figure in the JP community already).
And most of these campaigns aren't campaigns that Western fans can contribute to (and even if they can, there's a lot of overlap i.e Western fans can contribute to Rosa but they probably contributed to Solaris instead), so it all falls down to the JP community. Rikka's crowdfunding campaign was the last one that was a smashing success, but in the end it burned people by changing the type of product at the last minute and had to offer refunds to angry pledgers (she was originally pitched as a VOICEROID product but then switched development to CeVIO near the end - this made many people angry), so it's possible that people are being more cautious about pledging to a campaign in order to avoid getting burned like that again (the chances of it happening are very low, but if it happened once...)
So there's that, and I also think there's just too many crowdfunds happening in such a short period of time. JP fans are known for contributing insane amounts of money to these, but these crowdfunds typically were for VOICEROID products specifically. Talking banks are more popular than singing banks, and... a lot of VOICEROID fans don't really care if the product isn't VOICEROID, in all honesty. (Though CeVIO is popular too, AHS hasn't exactly been promoting these crowdfunds since they aren't involved. I know they RT'd stuff about Rosa on occasion, but it's a lot different from announcing it themselves and hosting entire livestreams around it like they did in the VOICEROID era. So Rosa's more or less just on her own.)
As for what will happen if Rosa fails... I'm not sure. ZAN-SHIN's started a Vtuber project which makes me think they want to use that to gain additional money, possibly in the case of this failing, but who knows. I'm sure they'll want to create Rosa either way since Cul's lore is a passion project, it'll just take longer.
This was a whole bunch of word vomit just to say I think there's a lot of reasons why Rosa's not doing particularly great sdoifjsdfi I think she'll still be funded eventually since there's a lot of love for her, but it will take a much longer time than if she were to hit her goal now. Her campaign is all or nothing, so if it doesn't reach the goal they'll have to start from square one.