Here in ga we call these things “mock oranges” and the trees are often found around old home sites. according to an article i read, they do repel cockroaches, with the bugs actually turning around and running away from the fruit and it’s smell. some people are allergic to the sap, which is milky in color, and the scent bothers some people as well.
i used to work for a veterinarian and we would occasionally get a call to remove one of these things from a cow or horse’s throat where it was lodged (if the owner noticed a problem soon enough)…or when we did a necropsy to see what the animal died of. they are hard as a rock, and my cousins (boys) used to have fights with them all the time when we were kids…heaven help you if you got hit!