Yes, I wasn't reading carefully enough. But you might want to reword "activate one control zone per round" to "activate a control zone once per round", just so players don't try to say that if they activate Overwatch twice in a round then it's okay because it's the "same control zone". It also might be a good idea to explicitly say you can only have one control zone active at a time (you don't explicitly say this, but it's implied by the fact that they only last one round and you can only activate it once per round) just in case someone figures out some clever way to extend the duration of the effect.In the control zone rules you can only activate one control zone at a time.
Oh, and also, I just figured out a good counter-tactic against the control zones, and I can't believe I didn't think of this before. A creature who wants to, say, move through a control zone to charge one of the Auxiliary's allies could simply ready an action to charge as soon as the control zone drops at the beginning of the Auxiliary's turn. (Since readied actions interrupt an opponent's turn, he would be able to get his readied action off before the Auxiliary could get the control zone back up.) If you don't want people to use this tactic, you could make the control zone a "Sustain Minor."