Hello, I was the one who did the the Project HL2XMod years ago. I thought I would get back at this project, and I got some progress.
I got Minerva to launch: https://www.reddit.com/r/HalfLife/comments/et2x71/im_getting_closer_to_porting_minerva_to_the/

Some info:
The Xbox port uses version 19 BSPs.
You can use vbsp, vrad, vvis from SiN Episodes.
For the SDK I use CSMSourceSDKLiteSetup.exe (you can find it on russian forum sites)

There is a special command option for vbsp and vrad (possibly some versions of vvis too): -xbox. It enables mandatory xbox optimizations and possibly uses the correct lighting designed for the Xbox.

The problem is, is that the SiN Episodes compile tools are missing this option, and other versions of BSP compile tools seem to still hold some (or all) of that code, but they compile in BSP version 20 - so it doesn't work for the Xbox.

These versions should be version 19 and they definitely hold the Xbox code (I know this from finding old log files on old forums):
vbsp.exe (Nov 17 2005)
vvis.exe (Sep 7 2005)
vrad.exe SSE (Nov 9 2005)

The problem is hunting them down. I have looked everyone for them, including old, late 2005 builds of Source SDK on various shady and not shady websites and the download links are dead. So unless someone has them, please share!