I honestly just used what Google translate spit it lmao. I'll fix it.

But, my guess is they picked the band name to mimic what Ki$aki and co. did in the 90's, then ~split~ and became a gothic punk band with grammar abuse in its name shortly after (like they did with La:Sadie's). They really missed the boat on homage-kei by like 4 years.

Is this supposed to be romanized Kurobarazoku like K$'s band?

I think so, yeah. Unless Kijin stated somewhere else that they choose another romanisation, that would be the obvious way to romanise it.