In Digi Mesh, a Coordinator is only using when using sleep modes. Otherwise all nodes are considered routers.
More to the point is that DigiMesh is a Peer to Peer network. There is no “coordinator” in the ZigBee sense—any node can be nominated sleep dictator (sleep coordinator) but all it does is keep all radios in sync as far as sleep and wake times. There is no requirement that data aggregation and sleep coordination activities be shared by the same node. Any node can be the data aggregation point or you could have several data aggregation points per network.