As you can see in the attached zip file, there's nothing in the ACPI/Origin folder.
I tried your boot pack from this topic: https://osxlatitude.com/index.php?/topic/9941-latitude-5480-cannot-boot-installer/but then I couldn't boot at all (I saw the classic verbose boot and suddenly it turned off.)
By the Fn on by default, I meant it that when I press for ex. F12 it doesn't go to sleep as it would if I was pressing the Fn + F12 but just does F12 as on standart PC keyboard. I tried both F4 and Fn + F4, I also tried USB keyboard. Neither of them worked.
And for the synaptics touchpad, I'll try tomorrow at work - it's my work laptop but the keyboard is much more important to get working.
PS: I have clean 10.12.6 install with no kexts installed in the OS, just the ones being injected with clover in the attached file. And except bluetooth, Wi-Fi, audio, keyboard and trackpad, it works really great, including full graphics acceleration (gaming is great) and both video outputs. (I don't mind the bluetooth, Wi-Fi and audio, but the keyboard is a necessity)
PPS: Dell's Thunderbolt 3 Docking station also doesn't work, it only charges the laptop.