To appeal to the European court of human rights in Brussels there is no need for a country to be member of EU. Even Russian citizens can do so. I am quite sure that there were already numerous appeals to that court about language situation in the Baltics and Ukraine. All these appeals possibly were turned down or not accepted for consideration. Anyway what one can expect from a court that endorsed the Estonian sentence for a 80-years old partisan Vasiliy Kononov for participation in anti-Nazi fight? He was found guilty for killing pro-Nazi Schutzmannschaft members (local Nazi sympathizers who were given weapons by German authorities) during WWII.