Can a computer and its RAM function properly if the temperature of the RAM has been significantly reduced?
You have other things to worry about other than the temperature dependance on leakage current.  If you are dousing you board with refrigerant the cold surfaces will cause atmospheric moisture to condense out onto the surfaces which is generally not a good thing to be doing to your boards.

Whether or not this will retain your memory can only be known for that particular set of memories.  I've had systems be reboot-able at room temperature and other systems not at cold temperatures.  There are good chances that the memory will be retained given how conservative DRAM design is.

If you've solved the issue with your PCB becoming soaking wet and you don't exceed the temperature of the DRAM specifications (Which almost certainly is not -50 C ) then it should work.  The operating temperature specification are given such that the timing specifications are met.