Original sentence: They are officially recognized by several states of the ex-Soviet Union as an ethnic group, the majority of whom live in the Republic of Moldova where they officially comprise 76.1% of the population, and in Ukraine, where they constitute a recognized ethnic minority of 0.53 %
Edited sentence: They are officially recognized by several states of the ex-Soviet Union as an ethnic group, the majority of whom live in the Republic of Moldova where they are supposed to "officially" comprise 76.1% of the population, and in Ukraine, where according to Ukrainian authorities they constitute a recognized ethnic minority of 0.53 %