I would like use it like this in the phabricator. In the phabricator you write "{{T123}}" and get the link "T123:Page name". For Flow that might look like ""{{Topic:123}}" and get the link "T123:Page name""
Topic on Talk:Structured Discussions
Good suggestion. I've reported it (but I didn't find your Phabricator account).
At the moment, quoting this way {{Topic:Spbw1hvvrt474nb3}} does not embed the conversation.