Hi, for correct audio output you need set layout-id correctly in config.plist device properties.
I have a Dell 3490 and for this laptop I tested all layouts and for my case the better layout is 27 (15000000) and works all audio outputs/ inputs. but for your setup may be different.
I use Catalina 10.15.6 and Clover 5119.
you don't need inser kext in L/E only the kext in EFI/CLOVER provided by Hervé.
Realtek ALC256 layout 1, 2, 3, 5, 7, 11, 13, 15, 16, 21, 27, 28, 29, 34 and below (converted to HEX), try layout-id in our config.plist > Devices > Properties and restart you laptop. One of this may be work if you use Clover pack #3 provided by Hervé
01000000, 02000000, 03000000, 05000000, 07000000, 0B000000, 0D000000, 0F000000, 10000000, 15000000, 1B000000, 1C000000, 1D000000, 22000000
Leave "inject" in black/ null
Update 19/08 For Dell Latitude 3490 Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz (Brazil)
I Changed the layout ID to 13 or 56 if you use the latest ALC kext and used patched CodecCommander.kext With ALC256 based in this post https://techposts.org/fix-realtek-alc256-audio-macos-hackintosh/ and this solve like a charm my issue with Headphones in 10.15.6 (19G2021).
Clover+alcplugfix.zip
You need copy CodecCommander.ket from audio folder in pack that I already patched with ALC256 to EFI/CLOVER/kext/Other/
Don't use other kext or SSDT in folder EFI/CLOVER of this pack if you are not sure about you system is a 3490.
Unzip ALCPlugFix.zip in your Download folder and use Hackintool > Tools to mount in rw the / and then install the ALCPlugFix according to the tutorial in the link above using a double click in Install.command or via terminal. you can inspect the code if you want.
You can enable again the Gatekeeper after install ALCPlugFix.
After restart the system, the fix is enabled every time you insert the headphones . If does not work with layout 13, please try in other layout-id like 11 or 21.