For what it's worth, although the drug has worn down their emotional control a lot, I think that Mrs Augustus's reaction to 'Cosmo' (who knows if she decides to keep that name?) feels really genuine and I suspect that this is the Good Girl she's wanted in her life. I also think that Cosmo is going to be in the position of having to be the sane one in the household sometimes, which makes her plain puzzlement at Claire and her mother's actions funnier!
Where did Claire get the confetti, Tai? Well, she's either an animé character or a Disney Princess. Having accessories like that always available is part of the job description!
Dora's reactions in panels 2 and 3 are wonderful. Once again, we see the reaction of the saner characters to the comedic excesses of the universe in wonderful detail!
EDIT
Rewrote the first paragraph - Never post before coffee!