Hello
In my game, I used Tags for this.
It is very easy...
Make "enemy" Tag for the enemyes and use the Get Tag Count action.
When the enemy killed, and destroyed in game, the counter have -1 enemy Tag...
I hope you understand my english
You can use this with simple example : (GuiLayout Int Label)
// Enemyes: 5/ 2
prefix / int varriable from Get Tag Count action