So I figured out how to unscramble the raw UI background images and the bits that go on top of them,
they're stored in the files in little rectangles like this, and I found some stuff.
Pretty much the non Japanese languages on the JP1.0 & the non english on US1.0 disc are all in various states of translation and contain stuff from an earlier stage of development.
Here's an album of most of the stuff, if something isn't in English then it's because the eng folder didn't have it. Some are screenshots and some are dumps because my tool discoloured things at first, but then I fixed it.
The green tint to the 'Special Event Lineup 2' pic is just how it is, it looks like that if you put it in the game. The AZ-1 pic shows the square trophy place and a gold trophy in it instead of a small silver one.
All the dumped images from the various discs & languages are in
this folder, these include all 3000+ images from that directory not just the ones in the album so there's loads of car description and dealership stuff.
Also, none of these 'work' if you put them in the game, the cursor only goes where it normally would and takes you to the normal places.
Edit: I checked the available demos, their backgrounds are just the used ones and their foreground bits are blank