I think functionality of these components got interchanged in community with ID's are misguiding to the component title and description.
When these are added to there respective quilt it doesn't show anything.
<component id="forums.widget.related-messages-taplet" mode="slim" />
<component id="tkb.widget.related-messages-taplet" mode="slim" />
I've got both on our forum pages because I couldn't figure out which was which.