The newly–added Mazda Spirit Racing Roadster 12R '25 has a roll cage that can be painted in the Livery Editor. However, painting the roll cage has no effect on the car's appearance.
Please click on the images to view the full size screenshot
As the roll cage appears to be identical to the one used by the Roadster NR-A '22, I wonder if the NR-A's roll cage not being able to be painted is also a bug.

Additionally, in the Livery Editor, the default camera positions for the 12R when projecting from the front, rear, and roof are off–centre, being slightly to the car's right.

The red line on the car's body depicts the camera's default position, and the blue line depicts where the centreline should be. The purple line on the car's bonnet and windshield banner are properly centred, represented with a purple line in the above picture. There are other cars with this centring issue, although I only know of the Giulia GTAm as an example.
I hope these issues can be resolved when the car is updated to allow for tuning and disclosing its specs, because the 12R is fantastic fun when being driven.