It may be corps level artillery for North Korean formation only since they're already familiar with it, not intended to hand over to Russians for their use. If true it would suggest North Koreans are about to hit the front in large formations.
Koksan is being retired now in North Korea, when it was still widely used in service one use for it was targeting city sized (read: Seoul) targets for deterrence. I can think of a few city sized targets on the front now that Russians might want to hit.
It would be curious to know what Russians offered to get North Korea to throw these into the war. Maybe it's even Su-57!
I don’t think it will that as dramatic as that.
The Russians are winning comfortably, there isn’t any reason for them to throw NK formations wholesale into the fight. Especially when those NK troops, equipment and tactics have not been battle tested. Do you really want to risk having whole sectors fold if the NK troops are not up to snuff?
Not saying the NK troops will do badly necessarily, but the Russians themselves have plenty of history and knowledge about how unreliable allied armies can be more of a hindrance than an asset from their battle histories fighting the Germans.
If Russia wants to deploy NK troops to the fight, it would make far more sense to deploy them slowly and as part of larger Russian formations so that they can both evaluate their combat worth, as well as pass on hard won experience and knowledge.
What better way to start than with NK artillery? You have very easily slot a few batteries of them into the order of battle while keeping them relatively far from the front lines to ease them into things. At the same time you can embed some NK artillery forward observers in Russian frontline units to build trust and learn how to best co-ordinate their joint efforts.
Only after such trials have been completed and the inevitable teething issues resolved would you want to progress to giving NK forces responsibility for whole sections of the front.
As for compensation, I don’t think Su57s are needed. Some Su35s will already be a quantum leap for the NK air force.