Have not figured out what is wrong.
While I never did figure out was actually wrong, I did get this working.
Procedure:
1. Completely remove all VoodooHDA related components, including from any Time Machine or CCC backups (and/or anything the system can directly reference).
Reference.
2. Install a restored copy of AppleHDA.kext (put on desktop, using KextBeast to install to S/L/E).
Reference. In High Sierra, using Pacifist, you can find AppleHDA.kext in the same directory into which it installs.
3. Undo any changes from previous attempts at getting sound working, if you have done anything.
4. If you have any AppleHDA references in your Clover Config.plist Kexts to Patch section, either remove or disable them (removing is generally recommended).
5. Rebuild cache & restart. All on-board audio references should be missing.
6. CodecCommander.kext, Lilu.kext, and Fake_PCIID.kext were already in place, . I don't know if they are/are not necessary (particularly CodecCommander.kext), but that's what's on my system. I have these in E/C/k/o. Restart if you install these.
7. Use option II.2. from the Audio
guide, and ONLY II.2 - NOT 1 or 3. I put AppleALC in E/C/k/o.
8. Restart. You should have audio devices and no sound.
9. Edit your Clover config.plist as per #2, third bullet, in Quick Fix
guide. I did not execute the first/second bullets.
10. Restart.
You should have sound.