Hi M,
I think that if the NGV was wrong from the factory maybe it can be passing the hot gas/fuel between the CC and the NGV and this cause the problem
I think more the other way around, pressure outside chamber is higher than the inside so air will only enter the CC. Still if the CC backring doesn't fit correctly it will give a hotspot over there due to uneven air distribution. I had the same on one of my KJ's where the CC outer wrapper had become slightly distorted over time where the fit to the CC rear wall outer was bad. An air gap of 0.8mm on a 1/3 circumference on the bottom of the CC made the hotspot you see on the picture. When I simply "hammered" the plating to close the gap again the hotspot was totally gone, see picture withoud the red glow. This is a homebuilt engine so I can do what I like, for your engine I would however try to make the company fix it......
Rgds,
Gerald