I don't think you are doing anything wrong. In early versions of Trainz the splines clung to the terrain surface. They no longer do. It's probably just a bit flag in the spline points. However, I have not been able to figure that out, even by comparing binary data of Surveyor laid track and TransDEM ...
You will probably find several posts on the Trainz forum regarding this issue. But the damage was done a long time ago, and I'm afraid we have to live with it.
Well, the original idea was and still is that the TransDEM textures do not belong on the DLS, they were never intended to remain on a published route and should have been painted over. However, starting several years ago, some freeware routes were published as Trainz content, delivered with the ...
Thanks for pointing this out. Another and newer OSM client of mine still works, and I guess that one uses a request header that complies with the OSM usage policy. I will have to compare the two.
Google orthophotos officially stopped working for quite some time. You need an API key.
Once the route has been imported with Trainz Surveyor, TransDEM can no longer modify it (since T:ANE SP2). You have to import and position new tiles manually. Did you do that?