I heard from Sara that they have been expelled a few days after it happened. I just don't think that it's fair that they got away with it. I doubt they will be prosecuted when they come back. Most likely they will never be sent to study in other countries, but I dont think they will face fines or conviction, even though they should pay back to the society with communal work or something related to that matter.
In Austria if you report something like that to police, even if the injury isn't serious, which means hospital is not necessary, the court would give you a fine or send you out to clean streets as forced labour. I know a rich guy, who was trialed but instead of receiving a fine that he could easily pay back, he was forced to work for 100 hours (no pay for convicted workers of course).
The Hooligans should be happy that they didn't become victims of revenge. If the injured Chinese was a friend of mine, you can be sure that her honor would be restored. Force can be so persuasive. It can persuade others never to do something again. Never underestimate the power of fear!