Created an example for you that runs on a periodic timer so it will trigger as long as you have a baneling in each of the regions.
Trigger
Events
Timer - Every 5.0 seconds of Game Time
Local Variables
Conditions
(Unit type of (Unit 1 from (Baneling units in Region 001 owned by player (Triggering player) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))) == Baneling
(Unit type of (Unit 1 from (Baneling units in Region 002 owned by player (Triggering player) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))) == Baneling
Actions
Unit - Create 1 Mutalisk for player 1 at MutaliskSpawnPoint using default facing (No Options)
If you just want it to happen once for each time you bring a baneling into the regions you'll have to use a "unit enters/leaves region" event and switch out one of the conditions for a "unit type of triggering unit == baneling", and duplicate and edit the trigger so you'll have one trigger with conditions for each of the regions.
Created an example for you that runs on a periodic timer so it will trigger as long as you have a baneling in each of the regions.
Trigger
Events
Timer - Every 5.0 seconds of Game Time
Local Variables
Conditions
(Unit type of (Unit 1 from (Baneling units in Region 001 owned by player (Triggering player) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))) == Baneling
(Unit type of (Unit 1 from (Baneling units in Region 002 owned by player (Triggering player) matching Excluded: Missile, Dead, Hidden, with at most Any Amount))) == Baneling
Actions
Unit - Create 1 Mutalisk for player 1 at MutaliskSpawnPoint using default facing (No Options)
If you just want it to happen once for each time you bring a baneling into the regions you'll have to use a "unit enters/leaves region" event and switch out one of the conditions for a "unit type of triggering unit == baneling", and duplicate and edit the trigger so you'll have one trigger with conditions for each of the regions.