What's also interesting is that not all the orders have two connections, only orders 1, 4, 6 and 9 have two; these of which connect all to each other. This would mean Windrunners linked to Edgedancers and Lightweavers, Edgedancers linked to Windrunners and Stonewards, Lightweavers linked to Windrunners and Stonewards, and lastly Stonewards linked to Edgedancers and Lightweavers.
In terms of certain temperaments the orders have, including spren, I don't see too much of a correlation?
Perhaps they mean nothing, and instead the Voidbringer version of this diagram would be the flipside, like shadesmar? Random thought.
Something must be going on here I think, Brandon doesn't just leave things for no reason.