Greetings Henisee,
Extreme cold can cause varying degrees of damage to the nerves in the legs, as well as, the vital organs. If there is no frost bite they have a good chance for survival.
They do seem to still be suffering from
stress due to hypothermia.
Young birds do not do well in extreme temperatures. And,
cockerels seem to be more sensitive to low temps. The immune system is weakened, so they need help. They are in danger of a secondary illness like URI. If they start to show symptoms you will have to treat for that.
If they were in my care, I would keep them in a hospital crate, (they cannot compete for food in their current condition), out of drafts, with mild warmth for them, about 70 degrees.
Provide warm water with electrolytes for three days. The core temperature of both birds is most likely still too low. Right now they are struggling to maintain body heat, especially if it is still cold where you live. The shaking or shivering is the body trying to warm itself.
Provide warm cooked foods: cooked grains like brown rice, corn, pearl barley, cooked apples or applesauce, cooked meat protein, mealworms, fresh vegies like shredded cabbage, broccoli slightly cooked or fresh. You will have to see what they will eat, but they need to be well fed. Offer them their feed daily, but drizzle a tablespoon of coconut oil on it to boost immune system and metabolism.
I also like to use herbal teas to assist in the birds ability to heal. For hypothermia I would use Rooibos tea.
Here is a bit of info on it.
Rooibos tea: While lesser known than other varieties, rooibos is high in mineral content and has many advantages. It is known for calming muscle spasms and indigestion as well as possessing anti-allergenic and anti-inflammatory properties. Rooibos also works all the way down to the genetic level by maintaining chromosome integrity due to its anti-mutagenic elements.
It's high mineral content may help with the nerve damage in the legs. I use one tablespoon of the loose tea to 7 cups of warm water, let steep 2-3 minutes, strain, then add 2 tablespoons of turbinado sugar, or some other nutritious sweetner. Put the tea into a small waterer for the birds to sip. At first, they may not be interested, but with the addition of the sugar, once they take a sip they will love it. Later you can omit the sugar. Offer it instead of water for half of the day, then return their fresh water.
Echinacea tea is another excellent tea, which will boost the immune system and aid in healing. Use one tea bag in a cup of hot water, then pour into 6 cups of water.
If you have ever suffered just mild hypothermia, you know the feeling of fatigue, pins and needles in the skin, and just a feeling of illness. It takes a lot of energy and nutrients to rebuild the body once it has been damaged by hypothermia. But, your birds are young, and with time and care should recover.
You will need to re-acclimate them to the
outside day temperature before returning them to the flock.
These are my thoughts on your situation. I hope they are helpful.
You will get other advice from very experienced keepers, please consider these too. Then, you can decide what best fits your situation and resources.
God Bless
