The "aura adds to botch dice" issue has come up before, and I'm inclined to concur with Laertes' ond Direwolf's conclusions here:
https://forum.atlas-games.com/t/proposed-rulings-for-new-campaign/6946/1.
It tends to make high auras borderline uninhabitable by mages, easily doubling and tripling the likelihood of botches and twilight.
Even at +1/2*aura in botch dice, casting in a typical (?) covenant of Aura +5 give people about a 4% chance of botching... , we are talking about a 4x increase in probability (I know this is mathematically not entirely correct, but it is close enough. I can crunch the numbers if someone is desperate for them. 8) )
In a wizard war, this will mean the best option is to hide in a large aura and have as many mundane defences as possible... the attacking wizards will eventually twilight themselves (OK, this is exaggerated but you get the picture...)
Full Disclosure: It is probably fair to say, that this comment may be just 'sour grapes', given that one of my characters has been at the receiving end of this new rule last night 