Much more route trace info is available passively.

[BillyBag2]

If a node participates in a trace route then this is provide trace route info for that node.This also provides an incoming route, not just an outgoing one.

Also the route discovery packets contain passive route information. (Ignoring the destination)

So a routing layer on the map could be added to show incoming and outgoing routes to a selected node. Including routes the node participated in and route discovery that the node participated in, even if the route was not discovered.

Or a new layer could just display all hops deduced from any route data as a line.