Homophobic slurs without repercussion

I was sitting in a study room of a university and after a friend of mine left, three guys started talking about me in German, perhaps not realizing that I could understand them. They repeatedly used “Schwul”(Gay) as an insult, and said stuff like ‘thats so gay – and we want nothing of that kind here” while looking at me. I posted their faces on my social media but a mutual friend told them and they confronted me and I had to delete it before they let me go. The Universities response was not satisfactory, they made me research the names of these people even though I had pictures and the BA they were doing, and they got away with a formal warning. I ran into them for years after at the university which caused a lot of anxiety. The University should have a 0 tolerance policy for cases like this.