I think the point worth getting at here is that "lolicon" as a loanword in English has drifted considerably from its use in Japanese, specifically in regards to the relationship between lolicon and pedophilia. In Japanese, "pedophilia" is narrowly defined as a medical diagnosis, and "lolicon" encompasses more or less all sexual attraction to young girls. The early history of the lolicon boom in Japan is inseparable from the era of grey market child pornography in the 70s and 80s, something that was ultimately marginalized in favor of fictional content due to increasing legal and ethical pressure. Many English sources would have discovered the subject after this point and therefore come to the conclusion (out of ignorance)* that lolicons are naturally only attracted to fictional content, while the original meaning in Japan has stuck to this day.
In other words, "are lolicons pedophiles" is a moot point when discussing Japanese creators. The pro-lolicon argument for scenarios like this would instead be that totally simulated sexual scenarios between consenting adults are harmless, or even a form of harm reduction that prevents lolicons from targeting children. (I am skeptical of this, but it is definitely a really common belief in otaku circles.)
* Not that it would always be ignorant to use the English definition of "lolicon", since a few decades have passed and some people now identify with it.
---
Circling back to Shigure Ui though, multiple people have mentioned that most either wouldn't be aware of any controversy or wouldn't find her to be controversial, and it's a bit of a yes and no situation. While not everyone here is aware of Loli Kami Requiem, it quite frankly could be considered the most culturally relevant lolicon-related thing ever, amassing 100m views (more than almost every Vocaloid song), charting in Japan and South Korea, and being featured by numerous mainstream brands. The discourse surrounding this made headlines multiple times, and now that the dust has settled, the broad consensus seems to be something like "it's a dirty joke that doesn't really mean anything" and "probably don't show this on TV or around concerned parent groups". It's not out of the question for old tensions to flare up, but deplatforming this voicebank isn't really in the cards, most likely.
What interests me is how this reputation and the marketing behind this voicebank will impact the scene more broadly. It goes without saying that the overseas community will be totally at odds with this, but it might not be smooth sailing with all Japanese fans either, even setting the loli argument aside. Looking at the current marketing, it's as though they have every intention of writing Ui (canonically another character, 14 y/o) as an infantilized moe archetype like you'd see in a lot of slice of life shows. This goes against common wisdom that the Vocaloid fandom is unisex - a slight majority of fans are girls who like that they can relate to and project on the female characters, so the "cute" factor can't go too far without coming off as condescending to many. However, it's exactly to the taste of Shigure Ui's fandom, who could very well cross into the community in large numbers.
So if Ui is successful, would this embolden adult male otaku to take more control of the community? Or would the existing fandom effectively gatekeep them after all? There are also other factors to consider, like the usage of the "KAFU formula" and the relative unpopularity of VoiSona as an engine. Either way, this release seems bound to leave a mark in some fashion.