If the bug is about the blue lines at the far left and right of the window where the backdrop color used for the side border doesn't match the background color, then it's probably accurate to the hardware behavior. For example, the border in Concentration Room is white, causing noticeable white vertical bars at left and right on my HDTV. And in a Ninja Gaiden series cut scene, a blue backdrop color might not match the black background color of the text.
There is a possibility to
enhance games by assuming the border equals the leftmost or rightmost pixel of the background, but before implementing it in an emulator, I'd like to see how it might implemented in hardware. The left side would involve starting the rendering process at x=337 when the PPU normally idles for a few pixels, shifting the idling a pixel later. The right side would involve sample-and-hold of the last background pixel.