Make sure to share it to the open source community if it works ;)

I do not think that there is a simple way of achieving this. Statistics are usually based on metrics. And those metrics don't yet contain user specific content. You could try to write your own plugin, that for example populates one metric per user - SonarQube could then render it. But this solution implies, that you do some serious java programming.

Oups, you are absolutely right :) The Leak Period can help you to fail if there are new SonarQube warnings, but not compiler warnings. So your question actually is not related to SonarQube at all, right?

@gvasquez I updated my answer - feel free to ask if any question remains open!