...They do not have a rocket program. They buy parts on the black market and pay some old Russian Engineers to create fireworks. We cannot say if this is really dangerous or if it is only fireworks to please the ego of Kim Yong Un with no consequence for anyone
I think you need to go back and do a little more research Frank. They most definitely DO have a rocket program. Yes a great deal of it is based on olderSoveit-era technology, some of it going back as far as the SS-15, however a lot of it is much more modern (relatively speaking) SS-25 and newer. In the past they did have Soviet "mentors", however now the program is almost wholly indigenous, there may still one or two ex-Soviet missile experts on the payroll, the Kims are very untrusting of any outsiders and once they have figured out the basics, I suspect they got rid of everyone who wasn't a loyal NK citizen.
As for the "black market" - not really. This stuff trades openly, albeit quietly every day. Countries are like consenting adults; they can do pretty much whatever they want between themselves. It was shortly after the collapse of the Soviet Union (1993-4 IIRC) that Jane's Fighting Ships and Jane's Aircraft (as well as possibly others) carried full-page ads where one could, through a broker, buy their very own airworthy MiG 29, or FAC(M). That said, very little, if anything at all in the weapons department has moved from either FSU or China into the DPRK in a long time.