What happens to the people that did nothing but cover it up?
You mean Weakland? He's retired and thoroughly disgraced already. His own monastery didn't even want him back.
"Cover it up" isn't entirely accurate, though -- stuff was apparently known about this publicly, through court records, back in the 1970's. It wasn't a secret. Murphy was removed from the scene and apparently from active ministry but no further canonical action was taken against him.
That's Weakland's fault; not Rome's. He had all the authority he needed to pursue the case.