Since no-one else has replied I will put in what little I know (from experience) about the subject.
In general you cannot move built-in assets from one Trainz version to another. If you try to export them as .cdp files from the earlier Trainz version and import them into the newer version the texture files will not copy correctly producing a long list of errors because they (the textures) are in a non-standard format. This is not done to make copying difficult but simply to speed up loading and processing when the built-in assets are loaded and displayed in Trainz.
If you are trying to import built-in assets from T:ANE into TRS19 then there is a free DLC package that will allow you to move many/most?? of them across.
From the TRS19 Launcher:-
select Content Store
in the text box type TANE Assets
click Install
From experience this will not necessarily import all the "missing" built-ins.
If they're not on the DLS they should be available by installing the older routes as DLC, or by installing the pack mentioned above. If you don't own the earlier routes, then you'd need to purchase them.
