Please try this and see if it makes any difference. Remember to backup your existing, working EFI and copy/paste your serial, board serial, and UUID.
It booted, but was still stuck in 4K mode. I checked "about this Mac" and noticed it only had 31mb. My current working EFI uses 1536mb for the igpu.
It did seem to have less glitches though than the previous version. I noticed you changed the ig-platform-id. Were there any other changes?
Also, I tried to find a way to PM you but apparently its either not possible or a lot harder than it should be... your serial number etc is still in the EFI you posted for me to use.
EDIT: Does the unified efi use the platform-id from the previous EFIs? Or does it use the new one that is officially supported in Mojave? Could that be causing the problem as I'm still on High Sierra (and don't have the special MacBook build)?
Just thinking out loud...