As far as I know and what UTAU Wiki states, Al!ce.16 is a "selfloid" of her creator and she's quite known as an oversea UTAU.
Like others has already stated, it's fine to create an UTAU of persona. Nearly almost anything can be an UTAU (almost because you have to use a little common sense that character isn't racist or other way degrading).
I remember that when I started UTAU, I desingned a girl that had Miku's V2 clothes but blue replaced with light green and had same hair than SeeU but as light brown like nuts and small silk hat with a white rabbit accessory and her name was "Pupuloid" (my old username was *cough cough* Pupuomena and Pupu means bunny). And TBH I'm glad that she got never a VB or never shared her online, she was very poor attempt to make "own Vocaloid" I was weeb
When I got my first mic in 2013, I designed a new character: Aki. He was designed to be physically looking completely "opposite" than me: opposites sex, gold/blond hair, freckles, blue/green eyes... But I gave him almost same height than me IRL (I think to change his height soon to be same than me?), same age what I was in beginning of 2014 and his like/dislikes were same than me IRL in 2014 (back then I hated coffee and never ever could drink it but noways I love milk coffee???) and he has same personality traits that I think that I have.
Aki is not really a "selfloid" because he doesn't look physically what I look IRL at all but he's more like an Alter-Ego. Frankly, Aki has been also a thing that I wished to be. He has been my coping toy for years *ahah..*
Other UTAU of mine are basically just OC with a canon voice but they often have a tiny bit of me in their personality or in their likes/dislikes but I would say that Aki is the most "self-loid" of my all UTAU, he's the most like me(?)