I'm not clear what you are saying here... the prices for xONEx ex-CAI are now fixed by OneWorld in USD? I can't see how it could be the case that BA had a fixed USD price and AA had a fixed EGP one because they would very soon diverge. Individual airlines don't have the power to vary xONEx pricing.

But both AA and BA previously billed your credit card in USD doing a conversion on the day of issue from EGP. I have never been actually billed in EGP.