Dogs that are not socialized in their sensitive socialization period (up to about 16 weeks) are difficult to work with and sometimes never get over their fears. I have trained some aggressive dogs that have been "stunted" by the vet telling the owner to not let the puppy out of the yard until all vaccines are given, at about 16 weeks.
Sometimes, with intense socialization, these dogs will get better. Often they will not.
The problem with a potentially aggressive Cane Corso can not be overemphasized. Even if the dog responds 99.9% of the time, if he breaks loose and bites someone he is going to be branded a "dangerous dog". The next time this occurs animal control will probably take him and put him down.
The only potential solution you have is to socialize the dog even more. Make sure that he is used to going everywhere, and have everyone that meets him give him a treat. If this were my dog I would never take him out of the house without a good muzzle, both for his safety and the safety of others.
If you want to read more about some techniques that might help, you can read my article at https://pethelpful.com/dogs/dog-to-dog-aggression