hmmm i think the problem in the condition or the action before it. try this:
event:
condition : on mouse clicked
action1 : enemy spawn bullet
action2 : set angle (mouse.x + randome(45), mouse.y+random(45))
also to check if that random function work or no try to use this:
event:
condition : on mouse clicked
action1 : enemy spawn bullet
condition2:system everytick:
action2 : set angle (mouse.x + randome(45), mouse.y+random(45))
you will see that the angle keep changing while the bullet moving