You get a notification in your client when punishment has been given to a report.
It doesn't tell you which one, just that it has been dealt with.
Riot doesn't give a play-by-play on any reports, in-game or on their web support.
Actually they say:
For the sake of privacy, we cannot disclose any disciplinary action that may be taken, but we will investigate.
I have also gotten:
I won't be able to divulge the outcome of the investigation, but rest assured that if we can stop fraudulent activity here, we'll do so. Thanks again!