Hope that some day, Easter will have an agreed-upon date across Christendom, but until then, just try to agree to the same Sunday, region by region. Can someone familiar with Eastern Europe or Russia tell us if this attempt is made?
Until such time as all Christians are agreed on a fixed day for the celebration of Easter, with a view meantime to promoting unity among the Christians of the same area or nation, it is left to the patriarchs or supreme authorities of a place to come to an agreement by the unanimous consent and combined counsel of those affected to celebrate the feast of Easter on the same Sunday.(Cfr. Syn. Vaticana II Const. De Sacra Liturgia, 4 dec. 1963.)