I imagine the air up there is very
dry at -35C. So where do you suppose the moisture is coming from? It's got to be from your living spaces. Your wood stoves are not helping either, as the two main by-products of combustion are carbon dioxide and water vapor. Do you have pots of water on the stoves for comfort? But you have to be comfortable in your home and you seem to have done what you could to seal things off. The solution is better ventilation.
As mentioned earlier, the gable end vents are probably short circuiting the air flow from the soffits. The incoming air never reaches the peak and moisture collects there and freezes on the roof underside. The roof vents you have seem to be woefully inadequate as well, and not the best option anyways.
I still think your best solution would be to install a continuous, baffled ridge vent. This would insure the incoming air follows along the bottom of the roof decking and carry the moisture laden air with it out the peak. You would also need to block off the roof vents and gable vents after the ridge vent is installed. Be sure to do your homework to size the ridge and soffit vents appropriately for your region, and pay attention to suggested ratios of ridge to eave vents. The soffit vents should be somewhat larger capacity the the ridge to prevent air being sucked up through the ceiling.
This site looks to provide some good information:
And where are those pictures you promised? They may provide more detail of your situation and help people here help you better.