Few things I've gotta hit on.
Personally to me I don't mind weird references on Theophilia after all. Actually I really like the idea of Crime/Investigation involving youkais since due to their inhuman and often impossible powers they indeed would be capable of Perfect Crime, I wish something like that was done again, but better (I know White Names Spoiled Past did that, but again, I felt like it could've been handled better).
Regarding the reference, I don't think the creator is like that, Theophilia most likely however. Even in the teaser before the extra video he posted this,
which seems to be containing parts of "The Corpus Delicti" novel. All those references make her seem like someone who would be in an episode of "Making a Murderer" and I think it's interesting idea nonetheless? Someone appearing as a social stage 2 boss, there's no way they are actually a cold-blooded killer above the law, is there? I do think showcasing that truly the most powerful and disturbing things in Gensokyo are those small fries is a good narrative point. I was kind of hoping with ZUN doing this with Eternity after implying she's a Tokoyo no Kami, but he didn't really do anything of the sort so far.
I would normally say I look forward to the creator's next work... but Burnyuho already posted a teaser for it appearently?:
https://www.nicovideo.jp/watch/sm34227604Ancient Times except Nature. seems to be another Music album mimicing ZUN's games, music and artstyle. I'm not good at translating so I don't know anything else, but hey, it's something I suppose? Kind of weird for them to not post it on Youtube like he did with Uncreatable Idea. but I'm happy nonetheless

Also I was kind of hoping to learn more about Kazari because I did realize she was a kamaitachi even at the first glance, but I was kind of hoping there would be more to her. Ah well, at least it's funny she and stage 1 boss have some kind of relationship. I hope there will be more things like that with future game/album stories. Like stage 2 boss was a victim of stage 3 boss, which in return works for stage 4 boss and so fourth. It helps imo. Like in UC's case, the story is solid, but after reading the translation, Ai kind of came out of nowhere and the only relation to the plot she had was the she was mastermind's creation.