The train is changed in motion. Why can't this technology be examined for Queensland and NSW interconnection?
It is possible that the Talgo gauge change system is only for passenger vehicles with articulation and a single axle per vehicle.
It is not clear if it works for non articulated bogie freight waggons.
If it were, Talgo would be advertising in Australian magazines, such as "Track and Signal" or "Railway Digest".
Also, Talgo is used for SG and two wider BG (BG Spain and BG Russia).
It is not clear if there is enough room between NG wheels for the Talgo gauge change equipment.
As said before, Talgo advertisements of their wonderful system are conspicuous by their absence.
Also, the market for Talgo equipment in NSW and QLD may be too small to make it worthwhile for the Talgo people to bother.
There is also the "NIH" factor.
Talgo gauge changers date from IIRC 1950s, and may be obsolete technology.
BTW, the first Talgo trainsets were built in 1942, not long after the end of the Spanish Civil War.