Levels at the Academy for the Alt Event?

This was something that popped into my head and I figured it might be a question others might be interested in the answer to as well.

How do the levels/grades at the Academy work? For instance modern day schools are grades 1-12, Harry Potter it was your year. However when I asked on one of the KR facebook posts I was informed that our characters should be at the Academy no longer than 20 years, but if someone has been studying at the Academy for say... 10 years since they were a child, what "year" student would they be and how are those grades/levels determined? Just for a reference point when talking about our characters and where they are in their studies at the Academy.

I guess I'm just confused because multiple professors have said "first year" "second year" "third year" and it's hard to figure out where my character fits into those references and I'm sure others probably have the same issue.

In addition, “first year in my lessons” means that sphere? Or in the school?

Just because there’s stuff my character would want to attend and she has rank 4 spells but she doesn’t have any bardics/“enchantment” magic, so she can’t go? I just want to make sure I understand