As you can see in the manual article about the TiledBackground object.
The object is there to display the repetitive texture that has been loaded into it.
So no, no stretch or fit of the texture, those only happen in the Sprite object.
A way to "cheat" could be to have the TiledBackground on its own layer. As you know the size of the layout and you know the size of the image loaded in the object once it is loaded (expression ImageWitdth, ImageHeight) you can calculate the ratio of those and set accordingly the Layerscale and TiledBackground size so that it covers the layout and still appears with the correct "scale".