Make an option to backlight only some of the fn keys. It's hard that it's not any space between the f4 and f5 keys. So maybe a fix can be to back light only f1, f5, f9.

And also. The f12 MAJOR bug you have created. Not putting the f12 on the volup hardware position. Make a software fix that can replace the volup with f12. I have fixed this with PowerToys.