If you need help creating a bootable ISO of macOS Sierra 10.12.6 from Apple’s official installer (with French support included), I can provide the terminal commands.
"This copy of the Install macOS Sierra application is damaged" : This is often due to an expired security certificate. macossierra10126frenchiso
Never trust a pre-made ISO from a random website. If you need help creating a bootable ISO of macOS Sierra 10
This guide explains how to use a macOS Sierra 10.12.6 French ISO macossierra10126frenchiso
This specific file is typically sought after by users who need to:
: Note that many modern browsers (like Chrome) and apps no longer support Sierra. Consider using Legacy Patcher if you are trying to run newer software on this older OS.