I think I made it 
[actually it’s not working]
So I was trying to experiment with your recommendations I could not fully understand and it led me to the Get Actor of Class node :
With my Spawner as the Actor Class, I was able to access its variables I needed in my AI controller !
But I am very confused now as the Get Actor Of Class is doing exactly what I was expecting from Casting 
While searching on forums, its seems a lot of beginners like myself are struggling to find a way to communicate variables from one BP to another. I’ve red about blue print interfaces, casting, game instances and so on…
How is this working that easily ??