I’m honesty a little confused on why northern Ireland is canonly older than England, like, I don’t know how country ages work but northern Ireland is only around 97 years old. Shouldn’t they be at least younger? Or maybe it’s like with Germany where there was already land so they were born older?

I’m not sure either tbh. I just quoted it as it was. It’s not land that makes the nations grow older. It’s the existence of people and the strength of their culture. Strictly at face value without any theories over the matter, Germany was born as a child, not an adult. 

Source: Hetarchive, It’s a Treasure Box of Countries + World Stars Chapter 12.