Windows10にしてみたら、予想どおり、AppleWirelessKeyboardの「英数」「かな」が効かなくなりました。というわけで、前と同じように BootCamp のアップデータにあるドライバをごにょってしてしまうやり方です。 → AppleKeyboardInstaller64.exe

Mac keyboard function keys on Windows 10 not wo... | Apple Support Communities

I use a Apple Bluetooth Keyboard with my Surface Pro 3. After upgrade to Win 10, keyboard worked but without any of the enhanced functions. I did the following:
  1. Uninstalled as many Apple related Bootcamp pieces of software (ultimately all I had left was "Boot Camp Services" which I couldn't uninstall, but whatever)
  2. Downloaded Boot Camp Support Software 5.1.5640 (
  3. Unzip, and navigate to Bootcamp\Drivers\Apple
  4. In case of a fresh install, run BootCamp.msi (In my case Boot Camp Services was already still installed)
  5. Run "AppleKeyboardInstaller64.exe
  6. After reboot, all my functionality was back 

Boot Camp Support Software 5.1.5640

Apple Wireless Keyboard 買いました(2個目) | Blog @cinz 

Apple Wireless Keyboard を Windows7 で使うために買いました | Blog @cinz