Other keyboards, perhaps?

[Mkupolo1493]

I have the same issue with my K400+ but when I ran the script it said

Logitech K290 not found on this system

Does it really only work on K290's, or could the code be possibly be changed to include a command-line argument or such?

[risajef]

Same problem here.

[milgner]

Theoretically it should be easy to do. You could try changing the USB device id to match your device but whether the control codes match on those devices I have no idea.
I initially found these codes by running usbpcap on Windows and using the official keyboard configuration tool on Windows to toggle the Fn key setting, then using Wireshark to find what codes were sent at the time.