Several Wild Mage powers/features such as Chaos Bolt use the even/odd state of the attack roll to determine if additional effects are applied.
PH 274 defines what is an Attack Roll.
It looks to me that things such as RPGA rewards cards that allow modification to the d20 should adjust the result of the attack roll and thus the even/odd state.
Is this correct?
It's a bit hard to say for sure. Most people assume "attack roll" is different from "attack result." IE, my attack roll is a 12, but my attack result is a 22 (+10 base attack bonus).
However, now that you point me to PH page 274, I see the definition of an "attack roll" is what I've always called the "result."
In this new light, I agree with you, that any modifications are taken into account.