I think the "terrorism" that occurs to Misses Tutti and Frutti is symbolic because these ladies were completely innocent. They had done nothing to the children of the town but be different (deaf). The same is true with Boo Radley throughout most of the novel. The kids torment Boo and tell the neighborhood legends about Boo... they go after an innocent recluse. They know he won't come out. This is how things usually go, people go after those who are weaker.
Now, as for Boo's crime at 15, the group of boys chose to mess with someone who was stronger, a police officer. This wasn't smart because a person with power will exert their power to the full extent of the law.
Assuming that you are not including the attack by Bob Ewell upon the Finch children as part of the "Halloween Terrorism," I suppose that the other acts that night and on previous holidays could be considered childish pranks. On the previous Halloween in Maycomb, Misses Tutti & Frutti had been the victims of some "wicked children" who stealthily removed all of the ladies' living room furniture and hid it in the basement. Although this was of significant note for Maycomb, no one was hurt, and it was actually a pretty clever prank. Cecil Jacobs' attempt to scare Jem and Scout was also a minor attempt at putting fear in his friends' hearts compared to Boo's misbehavior as a teen. Boo and the Cunningham boys actually stole a "flivver" and then assaulted and locked the "ancient beadle," Mr. Connor, in the courthouse outhouse. The boys charges included assault and battery, and resisting arrest, among others. Although Boo's actions were not highly serious, they certainly were more considerable than the hiding of Tutti & Frutti's furniture.