The Recent User Contributions page section includes comments and posts that are visible to guests on a membership site, but it cannot be configured to show activity in Group forums that are restricted to specific users.
This feature request is about adding superpowers to the Recent User Contributions section to let it show content from the groups/forums that are accessible to the person loading the page - as a way for logged-in users to keep track of recent forum discussions in membership site groups.
Thanks for considering this!
-Tue