When you take the Attack action on your turn, any attack you make with that action can originate from your space or the echo's space. You make this choice for each attack.
Suppose an attack originating from the echo's space hits a paralyzed creature. The Paralyzed condition states the following:
Any attack that hits the creature is a critical hit if the attacker is within 5 feet of the creature.
If the echo is within 5 feet of the paralyzed target but the Echo Knight isn't, is it automatically a critical hit?