I see nothing happening because must use a 'for each Sprite37' in the ES of layout4, event 5. This due to, there is more than one instance of sprite 37 and the event picks all at once, and you must check up one by one.
Try that above or try adding before checking condition a 'pick closest to herosprite', 'enemy' sprite condition, this should work properly.
EDIT: this i speak about:
+ Sprite37: Pick closest to: compactorhero.X, compactorhero.Y
+ System: distance(compactorhero.X,compactorhero.Y,Sprite37.X,Sprite37.Y) Lower or equal 300
-> Sprite37: Set 'aggro' to "yes"
or
+ System: For each Sprite37
+ System: distance(compactorhero.X,compactorhero.Y,Sprite37.X,Sprite37.Y) Lower or equal 300
-> Sprite37: Set 'aggro' to "yes"