As a big history nerd, I'm in love with all of this. I'm genuinely curious as to how this will play out. It'd also be very interesting but doubtful, how the MC will react to Versailles Palace, as it was known to have a horrendous smell throughout the palace. I doubt the story would mention it but would be interesting. I am also curious if this will have the MC taking charge of France as the actual leader and leading them to prosperity. Would also be interesting to see if the MC would use her ner found influence to send an expedition to find Japan? I know that the Portagues were the first known to find Japan, but I'm not sure how well other European nations knew. But would be funny and interesting seeing her get homesick and spend large capital on sending ships to Japan. Then interactions with Japan, such as demanding to go on a ship over. Honestly, the alt-history scenarios are just getting me excited thinking about it.
Then again, it'd be funny if she goes there expecting to speak perfect Japanese, but turns out she no longer knows Japanese but only Austrian and French. So its like she's a fresh person hearing the Japanese for the first time. She never even realizing that she can't even speak Japanese anymore. Also be even more fun if she prepares herself for Japan, her thinking that it will be a bit different but nothing extreme. Just for her to be surprised.
Honestly though, the alt-history scenarios. There's so much interesting stuff that can happen! What if we got something like WW1 but there were Japanese troops in France. Maybe even WW2. Can you imagine the Japanese Super-battleship Yamato being docked in Brest? And a big ass battle happening between the Yamato and Bismark? OHHHHHHHHH! I love this image so much. Hell, I would love if this MC became immortal or kept reincarnating so she can just see what her homesickness changed. Give us God Queen Antoinette!!!!!!!!!
Edit: Also forgot to mention. But kind of funny that I read this manga now, as maybe two weeks ago my mother was just watching a film about Antoinette.