Okay i've noticed that supernova remnants are extremely dim around 5 sol luminosity. I think theyed be on average 1500x brighter than sol. So i have bumped up their luminosity and was satisfied with the results.
Change the code in the univerese confige to match this.
NebulaSNRLum 1500.0 // SNR nebulae mean luminosity
NebulaSNRLumDisp 1500.0 // SNR nebulae luminosity dispersion