Here are all the possibilities for two cubies with both faces misplaced in the locations that match the setup for Sequence 3C-E4 (additional misplaced facelets that are not part of the setup can be ignored). This shows that the sequence always fixes at least one misplaced facelet except for the last case which does nothing (fix that one as shown here). This means that while solving a scrambled cube you do not have to match individual facelets to the setup, you only need to make sure that both facelets are misplaced on both edge pieces. Although it may help to know that matching just the two facelets in the locations shown as blue on the first four cubes below will fix at least two facelets, three if the two on the right face are the same color.