That is the correct way to spawn when scanning those tiles, however with 3 cadets only 5 of the 10 alert tokens should have any effect, the rest should be "no effect" tokens.
Well said! This is a challenging mission, and one of my favorites! Make sure you have come as close as you can to rescuing the Thralls and putting together the Schematics before you start flipping the Alerts, because as you've seen your gonna have to get the heck out pretty soon after that. Also, a stun pellet is a very nice thing!