As mentioned in the linked thread, unfortunately this is a V-Ray limitation. Vlado has mentioned on their forums:
"[VrayEdgesTex] will not work on proxies for now; this is because when used as a bump map, VRayEdgesTex needs information for the entire mesh - obviously this is not possible with a proxy."
Both RailClone and Forest Pack use the instancing engine used by V-Ray proxies, so these limitations are shared as well.
If a solution becomes available we will certainly add it to our plugins.