This piece does not have an easy-to-follow storytelling style. It gives the feel of a story with many of the sentences missing, and the reader must make cognitive leaps over the gaps like a person traversing a stream on stepping stones. It requires a lot of assuming as to why people say and do certain things, and a fair amount of "Well, I guess what he means is XYZ..."
Still, with a few re-readings the reader can come to some conclusions about what the characters are probably talking about. (What is "ushering a queue"?)
Here we have a little glimpse of Nicolas Flamel and his ever-patient wife (not yet a widow) Perenelle, who are otherwise only referred to in Book 1, never encountered. Nicolas is portrayed as more crochety than I would have otherwise imagined him, and if he is so unfriendly (unlike Dumbledore) and alchemy is a dying art, then why would Jacqueline be so persistent in trying to become his apprentice? She is much better off with Dumbledore.
The time of this story must be when Dumbledore is still a young man, and apparently he has spent some time in Paris and intends to stay on there for a while, since he offers this newly-married young woman a post as his assistant. How did she meet him, at her young age? Perhaps during the fifteen days of the International Alchemical Conference.
I would not care to read an entire book written in this style. It is more obscure than I prefer, and while I enjoy puzzling out a mystery (what do these facts and observations lead to?), I would rather not spend my time puzzling out individual sentences. But that's just me. This story has a certain stylishness to it, and I'm sure some people would appreciate its unique essence.
You wrote this really well. I wonder how Jacqueline and Dumbledore will get along! And maybe you've heard of it, but if you like Flamel, you should read "The Immortal Secrets of Nicholas Flamel" series by Michael Scott. Keep up the great writing :)