If they can identify people involved, they can issue arrest warrants and a red corner notice via Interpol. That can make travel very difficult for the people in

If they can identify people involved, they can issue arrest warrants and a red corner notice via Interpol. That can make travel very difficult for the people involved and they'll essentially be unable to leave their own countries without risk of arrest. They won't realistically ever be able to prosecute, but they can make life a bit uncomfortable as a gesture. And if relatives or friends of those people vacation in Switzerland, they can always pull them in for "questioning about a suspect" as another form of harassment. Small countries can never threaten a big state realistically, however they have the ability to harrass people who work for these big states in the hope of discouraging future action