I'm the support agent that is handling the issue on the other ticket you mentioned. If this is a similar issue, you need to contact Woocommerce Support for further assistance.
But for now, I would need to take a closer look at your site. So I would need to request temporary access (WP-Admin and FTP) preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed
Your following answer will be private, which means only you and I have access to it.
✙ I would need your permission to de-activate and re-activate Plugins and the Theme and to change configurations on the site if required. This is also a reason the backup is critical.
I tested on the staging site and I'm unable to replicate the issue as the form is showing normally in french.
So I'm wondering if this is could be related with caching. I'm using Varnish, Redis Cache Pro (I tried disabled same issue), WP Rocket, and Cloudflare.
Unfortunately I'm unable to provide credentials on a production site.
The issue is not gone and it's still present on the production site. The issue is just not present when site is coppied in staging environement with no cache.
Could you please try deactivating all cache plugins on your production site? Then, if possible, please try deactivating all 3rd party plugins one at a time to see which one is causing the issue you had there.