A few things you didnt mention. Ashen Veil players have access to the Sacrifice the Weak civic. This halves their food needs and allows them to survive on hell terrain much better than anyone else.
The AC is not "evil", think of it as physical manifestation of war. In general the AC going up is intended to be a bad thing for everyone. But there are some advantages of it. It allows the creation of some units that can't be made without it. It strengthens units with the Stigmata promotion. It increases the amount of creatures that will come through planar gates and the chance they will (the Sheaim are the best served by a high armageddon count). Spreading hell to non-AV lands is advantageous to AV players since other players cant use sacrifice the weak. It also gives access to Sheut Stones which strengthen your creatures.
There was never a time when hell spread to good lands
As a lot of other people have already said, yes sacrifice the weak civic is powerful, and makes hell not quite as bad for evil races. However, this is completely irrelevant because:
1. Sacrifice the weak is better again
without hell. I don't think the solution is just to move it back to infernal pact, because that just encourages people to summon hyborem and then quickly kill him to stop hell spread. Perhaps it would make more sense if it had some kind of synergy with hell instead.
2. Other religious civics cope just as well with hell. Especially the Leaves one (mass health anyone? has the same effect as doubling food in a hell scenario, plus it has +++ happiness).
3. It is totally irrelevant that hell hurts AV races a bit less, because it
doesn't hurt good races at all. Neutral races also get less of an effect, because hell will only spread in their lands at a high AC. Plus they can just sanctify it.
There are a few advantages to hell, as you said, but they are far outweighed by the costs. That game I played, I was almost overwhelmed by the grigori, because I a) didn't get any sheut (and AIs hate trading) b) there was burning sands over the top of my iron and c) all my cities were losing population due to the sudden lack of improvements/resources. The game would've been much easier if I had just never summoned hyborem at all.
About the AC:
I thought 'fire' was essentially about the battle between good and evil. 'save the world, or destroy it'. All the ways to raze the AC are evil, and all the ways to lower it are good. Surely then, having a high AC would be a good thing for evil races, and a bad thing for good races? It makes no sense to me balance wise that AV races should be suffering as badly as good races when they do something, flavour-wise, they should be doing (raising the counter). In difficult games people will always play to maximise their chance of victory- they don't have time to play around with flavour aspects that don't give them an advantage. Stigmata and Beasts of Agares aren't enough. Stigmata isn't really that useful when my rosier has just been killed by the 100 AC event anyway, and the Order has suitably powerful counter-units that don't have any AC requirement at all (which totally rape beasts of agares due to their anti-demon promotions).
What i'm trying to get at is, there isn't really any huge incentive to raise the AC if you are an Ashen Veil player. Sure you can and it doesn't do you too much harm compared to others, but at the same time it is often advantageous to keep it low, especially if you are winning. This seems totally counter-intuitive to me.
There are a million ways of making the AC just that little bit more interesting and involved in the game strategy. Increasing the strength of the AV a little, but tying them much more heavily to the AC counter perhaps. Maybe make the power of all AV disciple spells linked to the AC, or their civic get better as the AC increases/hell spreads. There's also all the things I suggested in the first thread. None of these need to be imbalancing, it's just a matter of keeping the AC involved and working like it should be.
Oh and sorry for the long post again... my head kind of explodes with ideas and they have trouble getting out on to the page
