I do see why Foreman rather assumes that it is reasonable to back-project modern ideas about sexuality onto the tangled emotional life of Georgiana, her husband the Duke, and Bess, the adventuress who was his mistress, but would quite often dump him to go off with Georgiana when the Duke and Duchess quarreled about Georgiana's gambling debts. Oddly, Foreman does not pick up on the way Georgiana and Bess quote the Book of Ruth at each other - which is one of those things which always strikes me as liable to be lesbian code when it crops up in a context when one is looking for such things.
(There is a tendency, I've noticed, for people to assume that because the Jacobins were intensely homophobic, and subjected the goings-on at Versailles to a pornographic imagination which led to, for example, the Countess de Lamballe being killed and her body desecrated in a quite horrible way, that therefore we should not think of the deep female bonding of Marie Antoinette and her circle as being in any sense lesbian. Sometimes if it walks like a duck, it's a duck even if people kill it for being a duck.)
Georgiana has this odd proto-steampunk thing going for her in that she sponsors public displays of hot-air balloons as well as the careers of rising divas (not rising in the sense of going up in balloons you understand.) She and Bess and Caroline's mother Harriet got stuck in Switzerland as a way of staying safe during the Jacobin Terror, and seem to have been involved in some sort of system for getting letters, and occasionally people, out of Paris - which may well turn up in the novel when I write the French Revolution section.
Another thing Amanda Foreman misses is that, for an upper-class radical deeply compromised by being involved with the more radical kind of Whig on the one hand, and various women executed by the Terror on the other, Georgiana had some other contacts that one really does not expect. Foreman mentions that when Georgiana was thinking of publishing her poetry, Joseph Johnson was the likely publisher, but I am not sure that Foreman realizes the implications of that. Joseph Johnson was the publisher and friend of people like Godwin and Mary Wollstonecraft, and of Tom Paine - a very surprising person to crop up in the life of even a radical Duchess.
I really do suspect that this whole crowd are going to wander into Mara's life in the adventure with the Goddess of Reason...