For as small a game as ToB is 12 sound like more than enough to round it out.
Looking forward to her hearing her interactions with Sarevok, Cespenar and Imoen. 7 with Haer'Dalis ! Whoah, were there that many more with the other tiefling in SoA? I don't remember that much interaction between the two of 'em, but it's been half a decade since I played Amber and I don't know if I ever brought the two of them along on the same journey. Sounds like something I need to rectify in my next playthrough.
As for tossing out interjection suggestions... In Watcher's Keep there's the gambling cambion and extended mentions blood war mention in level 3 of W. Keep. Also, I think a number of npc's speak up about the "Imprisoned One" or the choice one has to make in his regards to that last level.
I can't think of too much interesting in Saradush. There's an interesting part in the prison where the vampire big bad waxes poetic about how she stands no chance against you, a comment there about how powerful Amber and the Bhaalspawn have become at that point (or perhaps not so potent, given a planar perspective) could be interesting. The relationship between the witch and the Yaga Shura is one of the more interesting set up's in the game; maybe an opportunity for her comment.
Then in the second half, well in Amkethran there's the lich with the Soul Stone and the smugglers (another opportunity for a parting shot at Saemon is often at the top of people's lists). In Sendai's lair, I've always thought it weird that the party can go 1,000 corpses deep in duergar gladiators without batting an eye. I know our favorite Bhaalspawn and company have more than exceeded the kill count of most any figure in Realms history, but it's a passing curiousity that no one complains about being forced to mow down slave warriors. In Abzigal's abode, meh, I dunno; that one's so campy I just try to get in and get. And Balthazar? I dunno, I don't think people play the vanilla ending much at all anymore with the option for Ascension on the table.
Oh, lastly (thankfully, this post has dragged on enough) there's the personal trials that the Bhaalspawn goes through. While I don't think anyone would want or expect an interjection for each one, a chance to confinde in Amber after an especially jarring one (where the PC is monologued at by his/her mother seems an interesting choice) seems both in character and fertile ground for popping in a comment. Of course an interjection here might not translate so well for P2 romances. Okay, done bending your ear regarding interjections.
10 epilogues? Eeeee!