Mac Studio: wrong keyboard layout on login screen

Since the second login appeared to be the desired and correct configuration. That leads me to believe that the language settings are not making it to the pre-boot authentication screen. Because all Intel w/T2 and Apple Silicon (M1 / M2) Macs are hardware encrypted at the factory. They need to give you a login screen immediately to unlock the disk and then continue booting whereupon macOS will sign in automatically to the real login screen without showing it to you and drop you into the desktop. Safe Mode boot reveals both logins and asks you to login to the second one. The first pre-boot login is not online with any networking, it's sort of a faked login screen with just enough code running to prompt for the password and handle resetting the password. Once it unlocks the disk you see the progress bar indicating that the actual operating system is booting. While Apple makes this look very attractive, it's far from informational to the user as to what is really going on under the hood so to speak.

So again, the problem is that the pre-boot authentication is not presenting the French keyboard by default but is using the USA one instead. The second login reached via Safe Mode could be reached in normal mode by logging out and not restarting the Mac. If you do that, it should be the French keyboard setting.

There is a preferences file in your user Library and another in the global /Library/Preferences that are the same. When you configured your keyboard / language settings those settings were applied to your user Preferences but not the global preferences.

Try this:

• Open Terminal
• Type the following:

sudo cp ~/Library/Preferences/com.apple.HIToolbox.plist /Library/Preferences/
sudo chmod 644 /Library/Preferences/com.apple.HIToolbox.plist

You will be prompted for your Mac password and the cursor will not move, just type in the Mac password and press Return.

The command sequence means:

Super User Do, Copy (the User Preference File) to the global all users Preferences location

Super User Do, Change File Mode permissions to Read/Write for User (root user god account) and Read Only for group and other users.

Once you've done that restart the Mac.

I suspect the root cause of the problem is that you didn't set everything to French which is what a full-time foreign user in France would do. i.e. system language and keyboard. You want to have both English and French. The is quite possibly outside the scope of what the Apple macOS Developers designed originally. The workaround to this scenario was found on an older Apple Community Discussion post here:

[ Credit to Linc Davis and _Pierre_ ]

https://discussions.apple.com/thread/7392283?answerId=32183925022#32183925022

Open System Settings then search for "language". In the results, click on Language & Region and ensure your preferred language is set. You might have more than one in the list. You might just want French only. Use the plus and minus buttons to add / remove languages. Then scroll down the results and look for Keyboard and "Language input methods" and you can add / remove the keyboards you wish to have. Select French and you can add the ABC - AZERTY keyboard. If that's all you need remove the U.S. or English, etc.

Then reboot and see if the defaults are French and ABC - AZERTY.

Try booting into Safe Mode which flushes some caches and performs some maintenance.

Shutdown completely, then press and hold the power button and keep holding it. The Mac will begin to startup, keep holding the power button until you see the Options screen appear. Then let go of the power button. Next hold the Shift key down and click on the Macintosh HD and there should be a change to the button below to Start in Safe Mode. Click the drive and the Mac will restart into Safe Mode. Login and you likely will see a second login. Once you get to the desktop, let is sit for 5min so it finishes running those background maintenance tasks, etc. Then click the Apple menu and restart normally. Test your language settings on the initial pre-boot authentication screen.