Yes words change in use, and yes 'gay girl' did not mean all girls are gay, but the coincidence is not without a little humour-or is that why you didn't understand IanC?
Also words such as 'transsexual', gender dysphoria, transgender, etc, so one can not expect to find them in historic accounts. Hugo is not the only one reported to have remarked on Sand's persona. Chopin was a friend of Hector Berlioz who although a composer of note himself, was also widely known as a critic and writer. Berlioz left references to this in papers, but obviously not in words that did not contemporaneously exist.
If it is the case the Hugo did in fact say those words, it is reasonable to interpret them in the available vocabulary of the day. Not that I have asserted anything. The point of writing what I did was simply to say to Unkraut that we can not say for certain at what point in history people were observed to showing signs of a different gender identity, because the language to describe it as we would now just wasn't there.
All rather obvious when you think about it.