Hope your colony picks back up.
I find the whole hibernation / cooldown stuff that people do for ants quite interesting as I'm a new ant keeper and going through the motion myself. I just recently decided to start a really really late cooldown of my CA02 Carpenter ant colony, mentioned in my journal located in my signature below.
Anyhow, the whole thing, being new, makes me nervous. Cooldown is not so bad as I plan to keep mines at 63-68F which isn't all that cold and I believe mines will still wonder around.
But I don't know about folks that keep them really cold, like fridge cold. Like signs that they need it, signs that they're accepting the hibernation, signs that they're ready to be taken out, good signs, bad signs, all that. That stuff makes me nervous. I've heard quite a few ppl, my guess is newer keepers, running into trouble, big or small while attempting to hibernate.
Hope you're able to post some pics / videos on your guys, I'm a picture / video kinda person and love seeing the ants that you guys keep. Good luck with your colony.