Sorry to double post, but it seems Techno Speech isn't behind Ci Flower either. Her design is set to be revealed at Nico Nico Choukaigi (specifically, the "Super Art Exhibition" which The Vocaloid Collection is hosting, held on the 29th/30th), so we'll probably get more information then.
I guess the only thread left before it gets clarified is that she's by the company behind The Vocaloid Collection (which is a seasonal contest/event for producers and artists to generate a bunch of vocal synth content for prizes, with different categories and rankings), which seems to be
DWANGO (The VocaColle site has a copyright DWANGO mention in their footer). Alternatively it could still just be Gynoid, but... probably not. If it were Gynoid I think they'd just revive their social media accounts and announce her there anyway instead of making a brand new account - that's probably thanks to being under new management at this point who don't have access to/have no desire to use Gynoid's existing accounts when they can make a new identity for her instead.
The funny thing is that on Ci Flower's official images that we have so far (the silhouette and the logo) the copyright is just... Ci Flower, like she owns herself. I'm not really sure why they're keeping the company a secret at this point still if it isn't Techno Speech or Gynoid, but I guess the only possible company left it could be is DWANGO. If it's not them either then it's impossible to guess. Unless the company is literally just called Ci Flower.
Anyway! It's not like any of this speculation really matters when we're gonna find out in a few weeks with her design reveal probably, but I just find the whole thing fascinating. I'm having a lot of fun thinking about it; looking forward to seeing what actually gets revealed.