I'm going to take a different approach. The highest possible sum of digits is 28, for someone born in 1999. Now 1999 itself doesn't work out as such a birthday student would only be 18 today, but it provides a limit for the earliest possible birth year, which would be 1989. The digits of 1989 sum up to 27, so that's out.

Now given a 4-digit birth year ending in 9, if we know such a person's age and their birth year's digital sum, we also would realize that for every year earlier that they are born, up to a maximum of 9 years, their age increases by 1 and the sum of their birth year's digits decreases by 1. So if the difference between the age and the digital sum of the birth year in xxx9 is even, we can find a solution in that decade. Applying this to 1999 (digital sum 28, age 18), we see that we go back five years to find a solution in 1994 (digital sum 23, age 23).

We can't find a solution in the decade going back from 2009 (digital sum 11, age 8).

We can find a solution from 2019 (digital sum 12, age -2). Go back 7 years to 2012 (digital sum 5, age 5).

The youngest college student in history that I'm aware of Michael Kearney, who graduated from high school and started attending college at age 6. Thus the concept of a 5-year old attending college is not too far-fetched. Therefore, I say that the university student was most likely born in 1994, but could've been born in 2012.