International olympiads & Commonapp

In my honors section, I've listed the medals I've earned in a few olympiads. However, there's not enough space to list the selectivity of the award and mention that I was the group leader. It's an international olympiad but definitely not well known and its name is over 7 words!!

I've been told that I shouldn't repeat info again so I'm not planning to add it in my Activities section. Should I explain what I did and the olympiad's selectivity in the additional info section? In the additional info section I've already pasted the abstract of my research papers, so idk if that's too much.