So… do you know if anyone has compared the Jadeblood symbols in the panel where Roxy summons the matriorb to the symbols of the new extended zodiac yet?

They have. The Roxy ones match the Jadeblood symbols in the Zodiac. Which is no surprise, since Hussie said the extended alphabet was developed for the game, which means a lot of these have probably been around for at least several years.