When we right click on a player in 2142cc and try to warn the player, the server chat never happens. The 2142cc log displays the command, text and admin who executed it, but no one ever sees it in-game. It doesn't matter what admin or whether the the text is a preset warning (i.e. spamming, idle, etc.) or a custom text.
I posted this on the 2142cc bug reports forum as well.