I'm finally done catching up, there were exactly 69 new pages since my last visit, which is, well, noice. I left the relay after Fauna's debut and watched the other three later.
Kronii: I'm definitely not a hornifag and even as collected and calm person as me was distracted by the booba bouncing more like water ballons or something from the first Dead or Alive game (same thing basically). Hopefully it will be toned down. While her normal voice is okay (as in: her "older woman charm" does not work on me), her speaking Japanese kinda did the trick and the "fuck-off" attitude works rather well.
Mumei: probably the least eventful debut for me, which is strange, because she had probably the most YT subs before joining Hololive. But the song was nice and I think she has all the necessary skills to entertain the viewers.
Baelz: the accent-switching is something else. Her Japanese is quite good in my opinion. Singing with different voices is interesting. Lots of energy, laughs, memes and so on will probably make her a powerhouse of this group.
There was no debut I was bored with. The biggest surprise for me was probably Fauna, because ASMR usually does not work on me, but hers kinda did and it's almost completely new experience for me. The most bland debut was Mumei, but I'm far from crossing her out, quite the contrary - I'm looking forward to her future collabs, projects and songs.
PS No, the biggest surprise actually was Josh not asking here wtf is going on.