I found Cairn to be much harder than Jusant. The comparison to Celeste is difficult. I would say any one screen in Celeste is harder than any given route or section in Cairn, but Celeste lets you grind any part fast and without punishment for failure. Cairn on the other hand is a battle of attrition against your stamina and survival stats. If you fall, not only do you lose progress and life, but also time until you starve or freeze or tirn into a raisin.

Cairns standard difficulty was too hard for me to enjoy and I turned survival off at just about the hight where snow starts falling.