First of all, KHU has posted the new TGS 05 trailer. It's not the full 8 minute trailer, but it's still worth watching!
http://files.filefront.com/4305959/
Now for the exclusive info. I found on the IMDB, that most of the Japanese cast has been added.
http://www.imdb.com/title/tt0390163/fullcredits
If you notice, voice actors for Seifer (Zack's AC voice), Raijin (Barett's AC voice), Vincent (AC voice), and Tifa (AC voice).
Now keep in mind
IMDB is NOT an official source and could be fake But since it was previously stated by Nomura that there would be an Advent CHildren based sidestory in KHII, it seems very probable.
And I also discovered an actress who is confirmed to play a role in KHII. WHo exactly, I don't know. But it is official, check her official site.
http://kristenrutherford.nowcasting.com/
Yes aside from the Trailer link, this was all discovered on my own.