MegaGlests' game mods menu let's you install many new mods. Even more are available on the MegaGlest Wiki and the Mods forum.
The name of the units are in their XML. You can change it too, but it is static, so other players can't change their names, without editing their names again.
Maybe instead of including them in the current language files they could be put into a faction language file? The xml would link to it.
Such a language files for techtrees is not yet implemented I think, So you'd have to go to glest_game/techs/magitech and its subfolders, look at all the .xml files and search for the names.