Original Title: La Vie d'Adèle - Chapitres 1 et 2 (Wikipedia capitalization)
Title card spelling of Chapitres is Chapitre.

@backfish wrote:

Original Title: La Vie d'Adèle - Chapitres 1 et 2 (Wikipedia capitalization)

(One of my favourite movies of all time ...)

For reference, take a look at the following old content issue report that @lineker replied to 5 years ago:

https://www.themoviedb.org/movie/152584-la-vie-d-ad-le-chapitres-1-et-2/discuss/525553f8760ee355d40d7e79

Title card spelling of Chapitres is Chapitre.

Hm, the title card confuses me a lot, because of the English title/words at the top! I assume this means the title card was taken from an English release -> and not from a French original release?!? What I mean is: I assume there was a release in the past with a title card that does not use any English words! I think this disqualifies this specific title card as evidence regarding the original French title!

The official website of the Cannes Film Festival uses "chapitre" almost everywhere - except for the poster! On the poster, it's "chapitres"!?!?

However, on this page, you can also download 2 pdf files in French and in English - and they use 2 different French versions:

• "Dossier de presse français La Vie d'Adèle" -> https://cdn-media.festival-cannes.com/pdf/0001/45/ea210c0fa10d5523a2754f8b17b27ee4b89f9a2b.pdf -> title: "La vie d'Adele - Chapitre 1 et 2"
  
• "Dossier de presse anglais La Vie d'Adèle" -> https://cdn-media.festival-cannes.com/pdf/0001/45/a4767acf8c8fd7535f454ebbc69391a7e2d4ff58.pdf -> title: "Blue is the Warmest Colour (La vie d'Adele - Chapitres 1 et 2)"
  

I don't speak French - and that's completely confusing to me. But these are actually the original press kits for the movie -> you can find the English version on the website of the official international distributor and they were also available at the official website (which is now dead):

https://www.wildbunch.biz/movie/blue-is-the-warmest-color/
https://web.archive.org/web/20131115135500/http://www.laviedadele.com:80/presse/

So, I can't decide what's correct here. 5 years ago, @lineker decided to use "chapitres" because that's clearly the correct one. I'm the wrong person to say if that's correct or not - so I'm going to keep this discussion open for another moderator.

Title card is from English Blu-ray release, so I don't know if it was originally used. There's no rule here that we must use the title card spelling like IMDb does.

The bigger problem I'm having is with: La vie or La Vie. It seems we're using Wikipedia's French capitalization rules, so La Vie is correct.