The anser is, indices does match. I found a bug elsewhere.
For some reason it seems that mesh edges with TopologyVertex index
pair.J doesn’t find any matching ditto
pair.I index among all collected (naked) TopologyEdges.
Either that or I have created some nasty bug somewhere. This is what I have:
Q; does TopologyVertex Indices (pair.I & pair.J) match for connected naked edges on a welded mesh (except for, perhaps, if a crease intersects with the naked edge?), … snip.