I know that with some romances from SoA, things happen with Aerie and Viconia, but with Jahiera, does it still continue until the big cheese is met?

Get the flirtpack, you can import your "love" into TOB w/o having to do the actual loving, it's a pretty seet deal. As for you question (should have addressed that in the first place lol), I think not, the romances only go on for a set time (or if you bomb spectacularly).

They continue until the very end, though the lovetalks become less time-centric and more event-centric.

Keeping spoilers to a minimum, could someone tell me when I will get a ToB Aerie romance dialogue? I've killed the orcish Bhaalspawn and I'm in the first outside location after Saradush. Does this mean something has gone wrong or am I being impatient?

Soon, very soon.

Thanks

Yes, you're being impatient. ;) It'll take a bit of time, but Aerie will warm up to you. Very much so. Soon she'll start the love talk again.

That's all I'm going to say.