It's currently non-intuitive, but the "recent comments" for the main section appear only to those who've selected to see the main section, and the "recent comments" for the discussion appear only to those who've selected the discussion.

Oh wow! I have been on this site for almost 2 months and have not realized this until you commented on it. Thanks for mentioning!

(Also, yes, this is a very counter-intuitive, and difficult interface feature that should be changed)