The times when SE doesn't act as a precursor to MELI despite having a big move are when the move happens on the same day to both stocks, meaning both stocks move up or down at a greater than average rate.
This strengthens the case for the correlation, and because they move so tightly together, days when SE moves while MELI remains flat (or near flat in consolidation) are reliable as serving to inform the future movement of MELI.
Please note that MELI is unlikely to inform the future movement of SE. The correlation is tight, but the moves are largely determined by the activity of SE.