RE: Leaking canvas
pmm,
Two things,
1. We always use a heavy fly on top of the wall tent, it protects against embers, reduces UV deterioration of the canvas, and it is warmer.
2. This seems unlikely but with a new wall tent I set them up in the back yard and hose them down inside and out and then let it dry. A new tent will actually have holes where the needle and thread went thru and it needs to be "wetted" once to cause the canvas to shrink back in around the thread to make it waterproof --- was this ever done (if not, I guess it is now with the snow). New wall tents can leak unless prepped. Also a rough rule is if the canvas is wet don't touch it, where you touch it can drip. When the wet snow settled on your tent did you try to "shake" it off by pushing up from the inside (a no no unless you have a fly) or did you go outside and drag it down off with a broom?
I recommend a fly to protect your investment and keep you warmer.
EKM