It seems to me possible that rather than a nefarious group working directed at Violet in particular, it could be that the group was doing a working against their political enemies in general. Because Violet exists in their imaginations as an real example from their lives of a perceived political enemy, she became a particular focus of energies. It could be my naïveté, but it just seems unlikely to me that covens would meet at seasonal celebrations to curse individuals they know. To curse political enemies in a more general way, on the other hand, certainly reflects the times.