Visual detail right before Nathalie transformed: the Peacock Miraculous sputtering between active and inactive states. I think we are also supposed to read the sentimonster going haywire when Lady Noire applied Cataclysm as indication of the Peacock Miraculous being damaged? Not sure though. (By the way, that's C A T A C L Y S M; the spelling you're using makes me think of 'catechism', which is, uh, amusing to contemplate in context of kwami are little gods!)

Correct re sentimonsters; the steering column in the doll head was the oversized edition of a hair clip of Juleka's, probably the same one that she was fiddling with at a couple points, notably including when Luka used it to put up her bangs before she headed over to model for Marinette. And apparently the correct word for the magical feather is 'amok'.