P.S.: your output is 4800x6000 pixels, which requires a lot of resolution.
A 100% scale, but a crop with a 16,3984x8,192 image in the Dome-Light based on 8*8 large squares.
The sides are concave, which is a benefit, but look at the squares of 8*8 pixels.
4800-6000_crop.jpg
I think the reflection works and shows details. Even I think that 16K is way too little for this camera setup.
I hope that clears the "dull" areas of the image. Please let me know if there is anything else; I'm happy to look into it.
Cheers