I did some brief testing on the whole "luck scales act as misfortune scales for the enemy" last year, but I had to give up as I didn't have the info necessary to interpret the results. As this was long before Edi did his recent random events list (and their triggers), and it was before I started compiling my own events list. (I actually gave up doing this test in order to start that events list so as to obtain the data I needed for this test).
I tested Order and Production scales though, and the effects of good enemy scales (ie. Order 3 + Production 3) were not reversed when they appeared in my provinces under enemy dominion (ie. They did not become Turmoil 3 + Sloth 3). Although when I tested Turmoil 3 and Sloth 3, both these scales immediately took effect on a province upon appearing regardless of whose dominion was there.
I only did brief testing on the Luck/Misfortune scale though, as it was very hard to judge results from the events I was getting due to the lack of a reference for the events I was getting (ie. No Edi's events list). Although I would say that I know how often bad events strike with a Misfortune 3 scale, and in my brief tests I didn't seem to be getting the same level of horrible stuff happening from a Luck 3 scale in enemy dominion. I guess the Dominions RNG going through a kind phase could explain that though
My suspicion is though that the Luck / Misfortune scale acts the same way as the Order / Turmoil, Production / Sloth and Magic / Drain scales. Which is.....
You can never gain the benefit of 'good' enemy scales unless you have positive dominion in the province(s). But any 'bad' scales in a province are always in effect, regardless of positive, negative, neutral dominion. And regardless of whose scales they actually are.
I actually laugh my arse off every time I see someone suggest taking Drain 3 and then using Heretics, Stone Idols or whatever to get the province to neutral or enemy dominion in order remove the -2 research penalty from the Drain scale. All I say to that suggestion is try it!!! The only way to get rid of the effects of a Drain scale is to get rid of the Drain scale
And this seems true for all the 'bad' scales from the three scale groups I've mentioned above.
I'll probably re-test Luck / Misfortune when I find time now that I have Edi's events list as a reference. Although can't see me actually having that time for several months, and I would be surprised if the effects of Luck 3 did reverse. (although as Squirrelloid indicates, it will probably all depend on just how the game reads scales when it comes to deciding which events can trigger. Since it may well read scales for events purposes irrespective of dominion)
Also, attached is a save to show my point on the Drain scale. Note the LA Pythium Serpent Priests still have a -2 RP penalty even though the cap dominion is neutral. (their RP would be 6 and not 4 if the effects of the Drain 3 scale had been successfully negated.)