Notification email in English despite a site in French.

Good morning,
When I validate (publish) the element written by an author who does not have the right to publish, he receives an email notification written in English when the element is published, even though the entire site is in French.
I looked for the text of this email and I think I found it in the "Flexicontent - Notifications for favorited content" plugin. So I translated the text of this plugin into French.
But the notification email remains in English despite the modification of the plugin. How should I get this email in French? I can't find.
THANKS.

The text of the email is:

Hello Test_Enregistré,

One of your items has been recentely updated :

Id : 2707
Title : Deuxième essai
Category : Mon Unimog\State : Publié
Link :  www.lesunimog.fr/index.php/content_page/...uxieme-essai?lang=fr

Cheers,
Les Unimog -  www.lesunimog.fr/ .

I answer myself : I modified the plugin language files in "administrator" > "language", file: "fr-FR.plg_flexicontent_flexinotify.ini".
Apparently, modifying the text in the plugin has no effect (except for the "Email subject" which is taken into account). Probably a bug, I think!

hello for translation use joomla string only