Well, I have played a bit more and tried having a look at this, both in worldbuilder and looking at the code (despite never having seen any python before in my life!)
It seems the 'local' column is a combination of the local factors you can see and some that you cant. Im not sure if it also includes the empire wide ones which arent displayed anywhere. None of these values seems to update during your turn, so if you move a load of garrison units into your city, for instance, you wont see the values change until after you have hit end turn. Even accounting for this, the change in revidx is not exactly the value in local.
For a single city the best (easiest) ways to improve the revidx seem to be:
1) Garrison - this goes up to -8
2) Happiness - goes up to around -9 (doesnt really start having strong effects until the city grows a bit
3)culture rate - goes up to -10? this seems to have a strong local effect, but strangely is only applied to the 'local' column and doesnt have a seperate listing on its own
4)State religion - especially under theocracy -6 (I think) as long as it is the only religion in that city
but the biggest influence of all always seems to me to be distance. So anything that you can do to influence that, especially: courthouses, imperialistic, get out of despotism ASAP!!
The previous game I played was on big and small map and I was heading towards domination (I had about half of the biggest continent). However, despite getting the pyramids and going to universal sufferage I was having big problems with the east most cities (mainly because I didnt want to move my cap off the west coast). Even at astronomy I was still struggling to keep the revidx down. I think I could easily have gone on to a win, but my point is that the distance penalty is so severe and I dont want to have to rely on pyramids as a crutch every game.
The distance maintenace is mainly a problem for outlying new cities that are built, and the revidx increases so fast there that you dont even have time to grow them a bit and build courthouses before you have problems. You can capture more developed cities but then the problem is just made worse due to nationality issues. I just dont see any way to combat these distance problems early game.
I like the posibility (in regular BtS) of being able to win conquest or domination in ancient -> medieval times but I just dont see how that could be possible under this mod. Capturing more cities helps keep the revidx down temporarily but I just dont see that you could keep up enough pace to avoid collapse, and if taking your whole continent is not enough for the win you are in a world of trouble! Maybe I will start a new game and give it a go.