The phrase "{actors} replied to the project discussion {topic}" (http://www.geni.com/tr8n/phrases/view?translation_key_id=228683) needs a {num} token for the number of actors so that singular/ plural verb forms can be used.
In fact all phrases containing "{actors}" (http://www.geni.com/tr8n/phrases?section_key=&search={actors}) need this issue fixed. There are some that use "{actor}" (e.g. http://www.geni.com/tr8n/phrases?section_key=&search={actor}+re...), but they don't have an equivalent for every "{actors}" phrase, and my newsfeed is full of reports of a singular actor which use the "{actors}" phrase instead.
Maybe I'm not understanding, but it seems to work in Spanish.
http://www.geni.com/tr8n/phrases/view?locale=es&translation_key...
You're right; I see what you mean. But trying to do the same thing in German (sorry, should have mentioned the language) only gives the {viewing_user} gender.
That context rule must not be active in German. Perhaps the Geni team Private User can respond to my earlier post about requesting management of German?