I have set the keyboard shortcut of microphone key and moon key to set keyboard backlight brightness down and up respectively. But when I set: system settings > keyboard > keyboard shortcuts > function keys > Use F1, F2, etc. keys as standard function keys to on position, pressing fn + F key does NOT initiate the keyboard shortcut. In this mode, pressing fn + F key should be the same thing, theoretically, as pressing the function key itself if "use f keys as standard function keys" was in the off position. I use a certain app that requires the F keys to work as regular function keys but I would still like to have this shortcut working. It seems to me this is a bug if in fact it is the case that fn + F key acts like pressing the F key itself alone when the above option is set to on. Correct me if I'm wrong. Thanks.
I actually fixed my problem. While "use f keys as standard f keys" is set to ON. I created 2 new keyboard shortcuts using fn + F key that set keyboard illumination down and up. Once "use f keys as standard f keys" is set to off those shortcuts don't work but the other ones that only require the f key pressed alone will work. Weird. Anyways, that's the solution for now.