[Edit (tomreyn): Since this is a feature request, I moved it here where feature requests belong. Omega's post responds to a post by softcoder.]Actually, not all of those are "built in". Resources (eg, food) are mod specific, and could only be translated with a
mod translation system, which does not exist in MegaGlest. Technically, you could create a mod in a different language (though don't expect many players unless you release multiple languages, as english is a majority language here, by far). Perhaps MG should consider implementing such a feature, as GAE has? In GAE, every command can be translated with the name parameter (eg, if your airship's attack command has the name value of "airship_attack", then in the faction language file, that's your keyword). As well, GAE lets all resources, unit names, level names, attack types, armor types, faction names, techtree names, etc be translated.
The translation also has a secondary purpose, as it allows tooltips (by adding the "tip" attribute to name elements), allows modders better control over casing (eg, MG cannot have a unit named "MIRV", as it will display as a very ugly "Mirv". Language files allow modders to fix this issue), allows modders to easily change the name of something without referencing it in a dozen places (eg, if you want to change the name of a unit, or perhaps fix some spelling in its name, you change ONE value in the language file instead of changing every instance it appears in the XMLs), and also allows others to expand translations to your mods (if you release a full english translation, even if many things appear unchanged (you might have a string that says "Airship=Airship"), others who don't know how to make mods can still easily make a translation for you.
Win. Win. Win. Win.