I see the swarm in a different way: it is a set of objects and effects happening within time but still identifiable from a single source. The synchornisation that you are talking about could be required but we can see the swarm as exploring an distributed system in time as well in space and using the external world as some sort of synchronisation support. The entities of the swarm are like messages with an simple associated behaviour. Synchronisation is complex and it is part of world exploited by swarms for a while but not really an behaviour of the swarm... Look at my examples: in choregraphies the synchronisation becomes the propagation of some effects in a distributed system, in the business process case the swarm happens in time but at a specific time you have few swarm members alive and just persisting the instance is some sort of synchronisation. In the case of smart contracts, the swarm is just at a logical level as part of consensus... May be is a bit strange to play this game but I find it usefull to imagine or even progam complex events as swarms of little entities with short lives and with fairly simple behaviours that can compose in complex behaviour of the swarm itself.