Yeah - trigger once only cares if the condition was true or false last tick. It doesn't matter what objects the condition is true for.
Your event 3, for example, will fire once when there is any Sprite with Color = 1, and then it won't run again until there is at least one tick where there is no Sprite with Color = 1.
In this case there is always a Sprite with Color = 1 so the event never runs again after the first time.