Mountains would have Snow Leopards, as per their real life counterparts, since they are adapted to the rough terrain, thin atmosphere and cold weather of mountainous climates.
"Snow" Tigers would be more suited towards the Taiga forests, just like IRL Siberian tigers. They would also be proportionally larger than tropical tigers, since a larger body makes your surface to volume ratio smaller, meaning your body dissipates less heat per unit of mass. This is why polar bears and penguins can survive outside of polar waters (which aren't really that cold compared to the -50°C surface)
The name Frozen Wastes implies a lack of large vegetation, ergo it's a Tundra, ergo the only vegetation found there would be those mini trees that look like weeds and grass. You won't find many large animals out there, moose and reindeer maybe, but not any large groups of (mostly) carnivorous humanoids, by which I mean Arctic Fox Keidran. There just wouldn't be enough prey in a given area and even if they domesticated moose or even fantasy mammoths, the sparse vegetation and unforgiving conditions put a tight limit on population growth even on omnivorous humans, especially with the mostly medieval tech level (see: Siberia, Lappland, Canada, Alaska)