Please keep replies on the list - I will notice them - and like I said I won't give up until it works :D
I wish you had OpenBMC installed so that I could access your system remotely and try stuff myself (via VPN and a router IP whitelist for security ofc)
Did your D16 come with an ASMB4 or ASMB5 module? if so I recommend installing OpenBMC and its coreboot patches - note that coreboot needs patching for them to play nice together since for some stupid reason the required patches have not been upstreamed so you would need to cherry-pick.
I am using v4.6 on my system FYI (no reason for me to update) and the only options I have changed are the ones I told you about before...all I can figure is perhaps I have a different version of the SP5100 that doesn't have the erratum or something to that effect.
FYI I saw you select build nvramcui as a secondary payload so you can mess with cmos options without recompiling as long as next time you shut off "Load default configuration values into CMOS on each boot"
Since your menuconfig options look fine...shot in the dark but try using grub instead of SeaBIOS as I use grub.