je pense que l'idée de falbalas est bonne mais - comme le mot ne veut rien dire en anglais comme en francais, neserait-il pas bon de laisser "fol-de-lols" dans le texte.

autre possibilité : fla-fla (ornement de toilettes dixit Larousse(qui fait écho à tralala - pour rester dans le musical puisque fol-de-fol - est inspiré des chansons populaires)

The popular songs of the 1850s were, no doubt, often silly and vulgar and contained but little wit as it is understood to-day, but they were frequently set to melodies which, though simple, crudely harmonised, and dreadfully inartistic according to modern standards, had plenty of go and possessed the faculty of sticking to the memory. Many of them terminated in a nonsensical chorus of "Fol de-lol" or "Doodledum-day," but that practice was fast dying out.