I wonder if there is a good ratio of temporary wormholes to number of stars in a tile, as well as a good range for how long they should last. Perhaps 1 TWH for every 10-50 stars in the cell, connecting 2 randomly selected systems, lasting an average of 1-4 hours of gameplay. If connecting to random, perhaps they should sometimes connect to systems in other cells, giving a temporary back door?I imagine transient wormholes as extra lines on top of this static grid. So the maps I am showing are the 'permanent' connections. For generating transient wormhole connections we can do any number of fun things (preferably long-distance and unpredictable).
As for a triangular grid, I like it, but why not go 3d and have a tetrahedral grid?