I have identified a temporary fix within the OS.
Select 'Line In' under System Preferences - this clears up the distortion.
Sometimes the distortion comes back if you click this window away, so minimize the window while keeping 'Line In' highlighted.
I am using layout-id 29.
I played around with this again today.
You can clean up the distortion by selecting 'Line In' within Systems Preferences.
A temporary fix, as the input jack/headphones sometimes it goes back to distortion.
Adding the layout-id under properties doesn't make any difference on my Lenovo X270. I already have 29 injected.
What I have found in troubleshooting....
Each time the audio becomes distorted, selecting 'Line In' in System Preferences makes the audio clean again with headphones.
I just used my posted EFI on a new x270 Catalina install - works flawlessly.
However, I did spend sometime trying to work out why the copy of the OS I made to the same SSD wasn't booting.
When I ran verbose, I do believe I ran into your error code.
Try going to BIOS, Security, I/O port access...
I dual boot Mojave and Catalina and can confirm the card works for wifi and bluetooth on both OS.
It should run natively.
Use the kexts in my EFI here: https://www.tonymacx86.com/threads/x270-catalina-time-for-optimization.288150/post-2086151