The most important point as I see it is that the
real level of luck, what the player will feel as lucky or not is not really determined by the luck scale at all.
With +3 luck and other negative scales, the player is going to see a veritable horde of catastrophes as many good events are prevented from happening and many negative are made possible. It may be that the player overall gets more positive than negative events, but the door is open for all but the most nasty events while many positive are prohibited.
Contrariwise, at -3 luck and very positive scales, while bad events are more frequent, some bad events cannot happen because the country's other scales are too positive.
As such, luck is a magnifier on the other scales, not a scale with an inherent worth (unless you are into void summoning or cross breeding).
And that is a LOT to pay 120 nation points for (luck+3) if it means that your other scales are less fabulous.
The issue is compounded by the 3 random event limit, as it means that, unlike all other scales, the effects of the luck scale does not scale with the number of provinces owned.
If you invest in order, production, or growth - you are benefiting all your provinces each and every turn with a tangible benefit. Likewise heat/cold for those that use it. Even magic, as it affects the MR and research of all creatures whereever your domain holds sway. And it works the other way as well, take negative scales, and you suffer in each and every province each turn.
Only luck is an exception.
Whether you have 3 provinces or 100, you will only get 3 random events. As such, the larger your country grows, the
less relative negative impact you get from misfortune and the
less relative positive impact you get from luck. Once you reach the threshold where you receive 3 random events per turn, the effect of luck peters out with further expansion - which makes those 120 points for luck+3 even less worth, if you expect to run a big nation.
In other words, luck is not just an exception, its functioning principle is very nearly the opposite of the other scales'!
Get rid of that 3 event cap, please.
