One idea (on ritual cohesion as opposed to artificial common cosmology) may be a collection of Deities and rites based on the divinations, prayers and meditations of our various groves and individuals.  We are very diverse - and we like it like that.  Our collective cosmology should consist of the beliefs of all of us - with the cohesiveness in the *applications* of those beliefs.   For example, on our list of Honored ones, we may have, among others, Athena, Odin, and Jesus.

Now, a rite to honor Athena  or Odin and a Christian service may be very different, but if they all contain similar ritual "parts"and if we approach those parts from a position that all are valid and due equal respect as long as they harm none, that teach respect for the Earth and values individuality, we would be functioning within our own guidelines.  We may not, however, be strictly within the dictates of various other religious approaches to these deities, simply by virtue of our inclusiveness.  In this way we conserve our diversity and maintain cohesion.   I would much rather see a collection of many rites and essays on many Deities authored by our varied folk and friends than a manufactured set of dogma that exists for it's own sake. 

At least for me, TDB is a philosophy that approaches the subject of the God/desses and religion in an atmosphere of mutual respect and support - not a set of specific myths from any one pantheon.