Americans are the only ones who regularly equate skin colour with ethnicity.

Yeah Romani in Western Europe are often white passing or straight up white, and mircrakagovia or wherever they are from is quite obviously an eastern Europe analogue.

Scarlet witch is probably white, maybe a bit swarthy

https://en.m.wikipedia.org/wiki/Wanda_Maximoff_(Marvel_Cinematic_Universe)

Wanda is depicted as a Sokovian refugee

Sokovia (Соковиja, Sokovija) is a fictional landlocked country in Eastern Europe that is the home of Wanda and Pietro Maximoff, as well as Helmut Zemo.

Eastern Europe more specifically