Very comfortable at -40C except when getting in or out of the Bag, Sleeping. snicker.
The inner isn't a blanket. It's a sheet that keeps you from sticking to the nylon and allows the Bag, Sleeping, to be issued to other troopies. You're missing the air mattress(absolutely essential to use an air mattress. Preferably one you do not blow up by 'cake hole'.) and apparently the bag too.
Those tags are for inventory control. Tags that give a temperature range are civilian. Think in terms of the inner bag being a summer sleeping bag and the whole thing as winter. As mentioned, take your clothes off. Your clothes go between the bags.