Hello Kalypso,
Because you're using on-board HDMI port, it will boot to a black screen when we set the device-id to 0x3E9B or 0x3E92 (or even 0x3E98 in 10.14.4). This is because macOS thinks that all of the video ports on the Designare are DisplayPort, so it sends the wrong signal type to the HDMI connector.
If you don't have a separate graphics card and must therefore use only the iGPU, I recommend buying and using a
USB-C to DisplayPort cable. You can plug this cable into either of the 2 USB-C ports on the rear IO panel and they will work.
But if you must use HDMI, you should set
IntelGFX to something fake such as
0x12345678. This will turn off iGPU acceleration, but this also enables the HDMI port. In post-installation you can add the Framebuffer connector patch
described here to properly accelerate the iGPU and enable HDMI at the same time.
If you can compress and upload the CLOVER folder from the EFI partition of the Mojave SSD, I can audit it for you.