Another usability observation: The .flow-menu ellipsis could be easier to pair with the message it belongs to. As there is no visual separation between messages – the user name on the left side is the only boundary, but the ellipsis is on the far right –, every time I accidentally open the flow menu of the next message...
Imo the flow-menu ellipsis just right from the user name would be more obvious, and closer to where the mouse usually is. The (talk | contribs) links also show up there, when the mouse hovers over the user name. The links could show up right of the ellipsis, or the ellipsis could hide when the links show.
The "Edited an hour ago" (.flow-post-timestamp) is also on the far end (actually the ellipsis menu of the next message is easily associated with it, causing the above issue). Imo this would be better placed where the "(talk | contribs)" links (.mw-usertoollinks) are, and hidden when the user links become visible.