No, nothing that elaborate. You only have to add a new section to the \Sh3 Commander\cfg\Randomized events.cfg file.
See this thread for an example of someone who wanted to have a number of different versions of the "Keep up the good work" radio message, the damage message and the crush depth message etc.:
http://www.subsim.com/radioroom/show...02&postcount=2
Also read the directions at the top of the Randomized events.cfg file itself.
Font on most screens is controlled by \SilentHunterIII\data\Menu\menu_1024_768.ini, but I have no idea which block in there controls that particular screen.