I don't think this works (we don't get free PENTHOUSE actions anymore), and even if it did, it would take a turn to be built, and even if we were willing to do that:
It's only 1 gallon of AV, but 3 CF and 200gc, which is a lot for shaving just a single turn off of the "cooldown." I don't think that's a good idea, we have plenty of things on the priority list that don't require being done in the Calamity room, we can just do those for two turns. It's a bummer, but it's a lot less of a bummer than I was worried that coming clean about the Lord of Change would be, so I'll accept it with a smile.
EDIT: BTW, Boney, if you are willing and able to field questions at this point about whether Mathilde would want the Room of Calamity for a particular action from the outset (I understand that Stuff might come up mid-action that might make her want the Room of Calamity when she hadn't before), I am interested in the "Create Orbs of Sorcery solo", "Attempt to codify Rite of Way so that others can learn it", and "Attempt to gain control of one of your Arcane Marks" actions. My expectation is, respectively, "yes" "no (either Room of Dawn and Dusk or no applicable room)" and "no (Room of Dawn and Dusk instead)", but I want to check, if those answers are available at this point.