In any case, my original point was that the party is about ten days' journey from Baldur's Gate, yet it's only a few days after the crash that someone from the city arrives on site. There's no time for news to have traveled so far and for someone to have followed up on it by normal means. Is it a plot hole, or did the abductions happen quite some time ago - long enough for an extensive network of agents to be deployed
I imagine that Cazador would have noticed immediately that Astarion was missing, and would send out someone to track him. Surely as a vampire lord of considerable power, he has plenty of influence far and wide, and magical means of sending messages. Also, by the time I ran into the monster hunter in my game, several days had passed (maybe not 10 but at least a week's worth of Long Rests) so to me the timeframe was believable.
I will however have to find my save game and re-play this bit to uncover the conversation everyone is talking about!