Is there any reason that Certamen totals would not be affected by the local Aura?
Surely a mage with Faerie Magic should always arrange that their Certamen matches take place in a Faerie Aura, whenever possible.
Likewise holy magi would benefit from having Certamen in a Divine aura.
One explanation is that it could be an abstraction since if the aura applied, it would apply to all contestants's every rolls and would end up being irrelevant. Another explanation would be that certamen is a test of skill, and the aura has nothing to do with it. If the first explanation is true, you'd be right that initiates of Faerie Magic and Holy Magi would have a bonus in their auras that would be higher than that of their contestant. But as the mechanics can be explained in different ways, there is no need imho to step in that direction.
Another explanation could be that because what Certamen is derived from (a variation of the Nightwalker virtue used by shamans to non-lethally battle each other) is also not affected by auras (since there is no related Nightwalker ability).
I read this somewhere in Hedge Magic Revised Edition.
I will have to look for that reference.
I am working from the viewpoint that Certamen is a non-lethal magical duel (paraphrasing ArM5 p89), that employs Hermetic Arts and Arcane Abilities. The actual dual has the magi in a trance, shaping the magical forces around them into symbolic phantasms (praphrasing p90).
As such, I am under the impression that the magical aura should equally affect these "magical forces", and each combatants' Attack and Defence totals, and possibly the Resistance total.
Though thinking about it, if the Magical Aura added to the Resistance total, Certamen in High Magic auras should take longer.
So just the Attack and Defence totals of Certamen. This aura modification should cancel out iff each mage were equally affected by auras.
But there is Faerie Magic, Holy Magic, and even Chthonic Magic, meaning some magi are affected differently by auras...