Attila - Diplomatic "Other" buffs/penalties

Spoiler Alert, click show to read: 

https://i.imgur.com/r4TFIAx.jpg

What are these, anyway? In the late stages of an ERE campaign, am experiencing large turn-to-turn mood swings among many of my puppets. I'd really like to keep the lid on these guys long enough to build my Imperial Palace and finish this thing out, but am finding it difficult to manage that....quite a few re-loads going on after inexplicable wars erupt. I'm not really scared of another war per se, I'm just ready to finish this Divine Triumph up and move on to another faction.

I can understand that things can't be all rosy. I'm big & powerful, they're not, lots of jealousies and grievances against me and amongst each other, fine, I get it. But seems like such factors are meant to be reflected by Great Power penalty, cultural/religious aversions/affinities, as well as things like gifts and treaties with other factions.

Which leaves me wondering what exactly goes into "Other"...which can fluctuate massively turn-to-turn. The lack of transparency leads me to believe that I'm inadvertently taking actions (or allowing conditions to persist) which are affecting my puppets negatively (and sometimes positively) that I have no idea about.

The only thing I can think of is that "Other" is a random modifier generated by a specific leader's reliability rating, and the amplitude of the buff/penalty is determined by the size disparity of the factions involved? In which case...I guess I really can't do anything about it, other than perhaps look for a serendipitous assassination opportunity?

Any ideas?

Could it be that they want some lands you hold? Just an idea. Maybe there are some hidden control goals that the AI's are pursuing.

Alternatively: maybe the number of detail slots that can be displayed is limited. So, after some certain number of bigger items, all smaller ones get bundled together in one category "other". That would explain the fluctuations: many small value items going up and down.

Given the way the game is I'd be willing to believe they apply script penalties/buffs.