For a short-term survival situation, I would optimize for energy and performance, such as calories and proteins, to keep my muscles moving.

Because you've provided no other information, I will go with the standard can size of North America: number 2 can, 20.55 fluid ounces, 2.5 cups, 3 7⁄16 x 4 9⁄16 inches outside dimensions.

If you will be including a multivitamin as part of your 12, then I'd recommend a Chlorella and Spirulina mix. You can look up their nutrition value.

First, I won't question your constraints, and focus on answering your question.

If I was limited to only 12 cans of food, I am attempting self-rescue to some degree (get to a checkpoint with an authority/agency with resources), and I'm by myself, then I would stock up on food high in proteins and fats for fuel, low in sodium to reduce thirst (canned food will always be high in sodium), and contain enough water that I won't be required to drink more water for digestion. I will be eating straight out of the can, as well. I would start with this article and find what works best for me, 25 Best High-Protein Soups on Grocery Shelves (https://www.eatthis.com/high-protein-store-bought-soups/#:~:text=Progresso%20Mediterranean%2DStyle%20Lentil%20Soup&text=If%20you're%20a%20lentil,grams%20per%201%2Dcup%20serving.).

Second, I wish to question your constraints.

Short-term is how many days?

How many people are in your group?

Are you attempting self-rescue, or are you sheltering in place to be rescued?

What are the environmental conditions?

What are your health conditions?

What is your water availability in this scenario? Is water part of your 12 cans?

Do you have time, opportunity, and means to cook and/or boil water?

I would try to buy some Plumpy'nut made by Nutriset. Last I checked, it's only provided via Unicef, who distributes it to malnourished and/or displaced populations. I would find an equivalent, if not the actual product.

I would try to find this product. I remember seeing on national news (early 2000s) that a software engineer got tired of stopping work to eat, so he manufactured a nutritious food in a tube. He said it was pretty simple: he researched what the body needs, cross-referenced that with known nutrition-dense foods to minimize ingredients, added small amounts of safe preservatives for MRE-like shelf life, and then adjusted slightly for taste. In the interview, he said he has already received offers and invitations from DOD, food manufacturers, Shark Tank, and a bunch of others. I have no idea what it's called, where to get it, or anything more than I've already shared.