I'd put money on not real. Two reason why:
1) If she is in fact in hiding from someone, then the very first place that someone's investigators would like is a wedding. This sort of thing is in chapter one of "How to Vanish for Dummies."
2) If she is so damn wise in the ways of hiding assetts, how could she not find the limit on an Amex Card - something any waitress in American can do and will do for a small tip?
Shows how much I know. I never think to look at weddings.
I think you mistake the wedding entry. Here is the operative text:
"I never would have thought this way before but now weddings are so very depressing to me. One night this week I awoke to a sudden memory of how profoundly lonely I felt on the Sunday after a Saturday wedding."
Pretty clear to me when I read it that the wedding was before she ran away. It was a memory she was recalling.
As for the Amex limit, I think the point of that entry is that that card was paid for by people working for her father and that his credit was substantial enough that she was pressed to tap it out. I knew a guy like this in college. His father would routinely put hundreds of thousands of dollars on the Amex card. He paid for his daughter's wedding with it, for example. The second card, which my friend had, was pretty much inexhaustible as a result.
I know John Richardson's reputation well enough to think that if he met her and he believes, she's likely for real.