This plugin provides you two widgets to show the average ratings or reviews of BuddyPress Groups on the frontend so that you can use it for displaying average ratings & reviews. There are two widgets- the BP group review widget and BP displayed group rating widgets.
BP displayed group rating widgets: Place this widget in a single group sidebar to display the member’s reviews on a single group. You can also set the widget like widget title, numbers of reviews to show, and default ratings to show.
BP group review widget: Place this widget on any sidebar to display the group rating.