Apparently when you right click on the panel and choose "add new item" when you're in the es_AR locale you get just Men not Men
I noticed and fixed this a while ago; though I'm not sure if it went into the 4.2 branch. Really, all the plugins need to be looked at; I don't think they all call xfce_textdomain() before setting the name of the plugin.
(In reply to comment #1) > I noticed and fixed this a while ago