Nokia has already translated S30, S40 and S60 into turkish years ago. They have just to update the few words between each new release of a phone or system.

With maemo it's completely different, the translation is surely totally different from the one on S60. They have to translate every package in turkish, in a way that's maybe not the way they're used to. Maybe there are technical reasons (as you said, maybe a problem with encoding), so it's possible they don't want to handle too many translations now. Maemo 5 is not really a mass market product. But Maemo 6 will, and for sure they won't ignore half of the planet this time if they want to sell their products.