Thanks for the link, I didn’t know about the generic import format. I had a brief look at custom Checkstyle reports to get a compliant format but I believe it’s unnecessarily complex to get this done within Checkstyle and I don’t want to set up tasks outside the build system.
Meanwhile I found New checkstyle rules doesn't show on Sonar issues list which also addresses this issue. The post suggests to use the Checkstyle package name as prefix to work around the filter condition. I just gave it a try and it works so I’ll take this route until SONARJAVA-4916 fixes the general issue.
Thank you for your help.