It's the "Publisher" column yes, you are right. My bad, messed a bit with my french there.
So here is a few examples of books with wrong characters in Calibre.
Please ignore the "extra space" I put to prevent parsed text.
https://www.kobo.com/fr/fr/ebook/silo-6
From : Actes Sud Littérature on kobo.com
To : Actes Sud Litt& #233;rature in Calibre
https://www.kobo.com/fr/fr/ebook/la-defense-lincoln
From : Calmann-Lévy
To : Calmann-L& #233;vy
https://www.kobo.com/fr/fr/ebook/le-...-de-l-anneau-3
From : Christian Bourgois éditeur
To : Christian Bourgois & #233;
https://www.kobo.com/fr/fr/ebook/m-le-bord-de-l-abime
From : XO éditions
To : XO & #233;ditions
Concerning the Synopsis case, there are line breaks too at the exact position in the HTML view too... I have no idea what I did wrong the first times I retrieved metadata with Kobo Books but I did it again this morning and there are no line breaks anymore and it looks good on both Calibre and my Kobo so nevermind.
It probably came from me messing a lot with all the plugins/options of Calibre. I am beginning with it and the beast is not that easy to use to be frank.
Sorry to bother you with this one.
Thank you for being that responsive by the way.