All right, since nobody volonteered, I've decided to test it myself.
Here is what I did:
In SP I;ve created nation with Turmoil 3, Luck 3. than I've played it until it expanded to about 30 provinces, and builded temples until I had dominion 10 in most of the provinces, adn luck 3 everywhere. As expected I was receiving about 3 random events per turn, most of them were good. Than I've convereted all my gems to astral and started chaincasting Banefull Star spell on my capital, until The luck there changed from 3 to -3. Than I kept it at -2/-3 for 10 turns, to make sure that there is no mistake, while gathering statistical information.
The results were not what should be expected, based upon KrisO comments. Despite having permament bad luck in my capital, due to chaincasting Balefull start, there was no significant changes in the global patters of the events in my empire. Other than standart "few units are cursed" events in capital due to Balefull Stars, there large majority of random events (about 80%) were still good, despite having permament bad luck in the capital. The capital itself was devasted once due to the plaque event, which is not surprising given that it had -2/-3 luck in it.
The results of this expereiment are very clear: the luck in the capital have no infulence over the random events good/bad ratio or event frequency.
All random events aredetemined on purely province by province basis based upon local scales, just as I said originaly in my very first post of this topic in this thread.
I guess this is the rare case where devs are mistaken, which of course should no be hold against them, given the very high compexity of the game and the fact that Kristoffer actualy said "If I remeber correctly" in his comments.
I hope the results of this test will be useful to some people.
Regards,
Stormbinder