Centers of Reformation can only convert provinces from the Catholic religion since that's the religion the Protestants split off from. For Orthodox or Pagan people it wouldn't make much sense to be 'reformed', because they're a different religion in the first place and don't have the issues that the Protestants would criticize (Papap power, indulgences).

Centers of Reformation can only convert provinces from the Catholic religion since that's the religion the Protestants split off from. For Orthodox or Pagan people it wouldn't make much sense to be 'reformed', because they're a different religion in the first place and don't have the issues that the Protestants would criticize (Papal power, indulgences).