Have tried this this morning, sound works on both DP sockets using both my original config (smbios 15.1) and your configN (14.3). I have external 2.1 speakers connected to the optiplex audio line-out port (pastel green one).
Similarly, the optiplex wakes from sleep on both DP sockets with a couple of mouse/keyboard clicks using both my original config (as long as legacy roms is checked on) and your configN
The only time the DP socket i'm using seems to make a difference is when I'm using my original config with legacy roms off. In the top DP socket, the optiplex wakes by mouse/keyboard click to a black screen and requires a shutdown via the power button to reboot. In the lower DP socket, the optiplex will not wake using a mouse/keyboard click but will wake if i press the power button, though it only wakes to black screen and needs a reboot as well. That said, sometimes it takes multiple attempted mouse clicks to get it to wake so maybe i didn't press enough!
I tried adding Mac OS X as a boot option and put it first in the boot sequence (since it was probably there when it was working due to recent mojave update). I swear that the optiplex woke from sleep perfectly using my config and option roms off on the top DP socket with this boot option added. It only worked once though and I haven't been able to replicate it
I shutdown to try it on the lower DP socket and it didn't work. switched back to the top DP and didn't work. Deleted and then re-added the boot option....didn't work, so not sure what happened!
On a side note, do you think how clover/OSX designates the disks could have something to do with anything? Sometimes when i open CC and go to mount EFI, The (empty) EFI on NVME drive is designated disk0s1 and my boot ssd (one with the clover EFI partition) is disk1s1. Other times its the other way around and the boot ssd is disk0 and the NVME is disk2 or 3 (depending what the windows ssd gets named). Point is, when opening mount EFI, the disks are not always in the same order...what governs this? Could it be a factor in anything?
On another note, the time was wrong again in bios when I went in this morning, same 2.5 hours ahead of actual time here. Not sure what is causing this but time in OSX is correct on boot so i'm ignoring it!