Well my concern is that it seems pretty unfair to present the party with a bunch of social challenges that they have no chance of completing, and to put them in a situation where they're going to get poisoned with no chance to avoid it happening.
I really like the adventure, and I like the idea of an adventure that's centered around role-playing, but I think it was a bad idea to make the adventure so completely dependent on a single skill.
Maybe I'll just skip the banquet entirely and have them find Lashonna some other way.