Pas beaucoup plot development. They suspect Gabriel and Delia, of course. While some French and American qualities ring true in the character, they are few. Clara does yearn to have the carefree giggle of a French woman. That characteristic does exist.
French women do have that sort of laugh.
It suggests that Americans are lazy, uncultured couch potatoes. And, he rightly points out that Americans don't have kitchens in their living rooms. But other characters act and talk in the way that's stereotypical. A true American expatriate would see right through the accents, for example. Take Anne-Sophie and her mother Estelle d'Argel, a novelist whose erotic novels wreak havoc on her daughter's sexuality.