Palettes translation was added for Bug #667402 "Colour palettes not translatable" (https://bugs.launchpad.net/inkscape/+bug/667402). But you're right, adding almost all gpl files to the translation list probably is not a good idea because lots of strings don't need, or are too complex, to be
translated. But I think we should keep Inkscape default, and maybe SVG and tango palettes in the list.
Localisation is especially hard for the palette Latex Beamer and to a lesser extent also the Ubuntu palette. The other ones are less of a problem. Inkscape default should in my opinion be localised, which is also the case for the SVG palette (the majority of the colors and new strings). The tango and echo palette are both small palettes and their localisation might be handy. So no problem to drop the other ones.
Regards Kris