This phrase
http://www.geni.com/tr8n/phrases/view?translation_key_id=212448 "public"
is wrong and due to it it is translated wrong way in most cases.
This phrase is appearing to the newsfeed/latest activities NOT or NEVER when somebody creates new topic in public discussion together the first post in it, BUT this phrase appears when somebody else adds second post to the new topic. As "actors" can be plural (Liist Rule) then sometimes it appears after 3rd or 4th post listing autohors of 2nd, 3rd etc posts.
Similar problems are with:
http://www.geni.com/tr8n/phrases/view?translation_key_id=227838 "curator"
http://www.geni.com/tr8n/phrases/view?translation_key_id=212575 "family"
http://www.geni.com/tr8n/phrases/view?translation_key_id=228675 "project"
It shall maybe translated/used as; "{actors} replied to the new public discussion {topic}"
BR
Lauri