So I think there are DXG files in the final installed game. These shouldn’t have any compression or weird things going on, but it is an archive of the BMPs in the game. I don’t know if there’s a DXG loader out on the interwebs, but basically it uses the same format as old Doom WAD files.
The courses should just be two layers. The background layer is the whole course, the foreground layer is just the walls that would cover the ball when it’s close to them.
As I said my post above, I really don’t have access to a modern Delphi environment, so getting into those files would be difficult.