@Frédéric-Coubard Can you try the following:
npm rm nodebb-plugin-twitter
Look to make sure the plugin is gone.
git clone https://github.com/a5mith/nodebb-plugin-twitter.git
Reactivate the plugin, restart nodebb. Go back to your live site and refresh your cache. Ctrl + F5.
If it still doesn't work, I'd need to have a look at a live example if you have it so I can debug for you. But cache and making sure you're on the right version should work.
(Also the official repo has been updated with my changes, shouldn't take long to appear on npm hopefully)