If I put a nearly full corny outside with ~7% abv liquid in it and it is going to be in the teens (Fahrenheit), will it splode or anything?
I once fully froze through a full to the top corny of Root Beer. It pushed through the gaskets and pushed the rubber around the lid up, causing some cracking... Corny still holds pressure fine. If you want it to pour though, the dip tube & the beverage line freeze easily. I (somewhat) regularly do this through the winter and it's freaking cold here (like -20C all the time )
I just wanted to chill a cider down to clear it and didn't have the fridge space. Your experience has caused me to reconsider.
In my case the freezing was due to my father-in-law helping it doing electrical work and unplugged the temp controller and just plugged the deep freeze in. He almost killed my slurry of ECY08 Brett. He would not have been forgiven for that.