I have an eshop in Greece and i want to configure its seo settings.
Its important for me to have greek characters in urls.
Althought, it automatically change them into latin characters.
In magento 1.9 it was done the following way: http://killerwhalesoft.com/blog/magento-unicode-url-key-products-categories-cms-pages/
It may help you to find which files need to be edited in 2.x - just make sure you do not edit core files, but put them in a module ;)