Consider that you have what looks like at least 6, and maybe 8, 50 watt halogen lamps. 300 to 400 watts total.
Incandescent lighting converts about 85% of that wattage to heat...makes your fixture more efficient as a heat source than a light source. Tape a thermometer to the ceiling after the fixture has been on for awhile to see how hot.
Also noted that your ceiling is peaked, and very narrow, so all that heat has nowhere to go.
While I agree there is some rafter ghosting, the black spots are likely from the paper on the sheetrock being overheated.
I would get rid of that fixture and replace it with fluorescent or surface mount fixtures with LED A lamps.