Cultures like the Avaar and Seers don't really see 'abominations' as abominations, but instead part of the workings of the world.
So in that, on many points of view, they would be facilitators of disaster.
But its likely that, say for the Seers' approach, the way they did it, the way the communicate with 'demons', 'spirits', resulted in situations closer to Wynne and Cole (so to speak), than Anders and the many rampaging entities in the games so far.
You can devote increasing resources on incessantly hosing down the wildfire or you can become great at digging ditches in response and let it burn out and have growth happen again. Either way, you're still gonna use a measure of fire for your benefit.
Rivain's culture won't let go of this because they've seen and heard of too many people gaining a spiritual strength to help their communities. Mages seeming empowered, not overcome. And the spirits communicated with are probably communicated with by stronger willed and wiser mages than normally. So when abomination occurs: 1)Its rare enough like with dealing with all of the elements, 2)There are other, safer and even possessed-by-helpful-spirits seers there to respond and protect people.
So to Rivain, the Circle trying to stop abominations (a term Rivain probably doesn't even respect) is like trying to stop all fires from occuring, or all flooding, or all earthquakes, or all violence of persons against other persons. AKA the Circle is the unnatural thing, if anything.
And with Rivain's relative isolation (they have a Circle but its not a big part of society, and they have Qunari but seem strangely resistant to embrace of it, they have national connection to the Chantry but won't worship the Maker; aka they keep to their own somehow), it works for them.
I think the theme of Rivain is that they go do what they want, face consequences and deal with them, and carry on doing what they want. That this is an actual legitimate course of action. You wanna pirate, go pirate. You wanna trade, go trade. You wanna magic, go magic. You wanna worship, go worship. You wanna build, go build. You wanna tear down, go tear down. They've built a culture from this and the result of it is people who seem to just do what they want as long as it doesn't interfere with the whole. Key word for them, so far as we know, is community. They're probably the closest as a 'family' that any nation on Thedas is. So yeah, if an abomination occurs, I suppose they'd respond to the threat and keep it from spreading, mourn the dead, and carry on - especially if the response to the threat was another mage/seer with their own spiritual power that they also used to help crops, keep the village warm, entertain the children, heal sickness. Another idea of Rivain is that if you mess with it, you mess with all of it + all of its connections. It has more extended connections than most other nations, even if it doesn't build on them and doesn't have as much strength to enforce those connections. It sounds like a place that all sides have been bogged down in conflict enough with that all sides overall decide more often that its isn't worth the bother. This is down to the Templar/Qunari influence on Rivain as well - the 'hedge magic' of Rivain is so prominent that it'd take a massive and very extended occupation and forced indoctrination of everyone to reduce it. And even then, its strategically placed to not last too long in a strong way to any 'invader'.
Rivain is one of my personal favs on where to go in the series. I'd love it for DA5, or at least DA6 - assuming DA4 is all or largely Tevinter. The characters we know from it are headstrong and may have a reputation as scoundrels, but often respectable ones that show that one can live as more than just a force of order or chaos. They'll fight, but not always. They'll establish law, but not always. All in all, they get along, and know that getting along doesn't necessarily mean abstaining from any particular action or behavior. They're very 'alive' and I'd hope that any portrayal of magic in Rivain, similarly, has Circle magic (overall) seem rote, Tevinter magic seem simple, Qunari magic seem dumb, and Elven magic seem outdated. I don't expect them to be the most powerful of magic practitioners (thus keeping them on a more equal power level in the Thedas setting), but I expect them to do amazing and cool new things as plot addresses them. In that sense, I'd expect a Rivain/Rivaini-centered DA to have the highest chance of having a protagonist that has most hedge mage qualities. Rivain Don't Give a Frak.