Only the ancient FIT v12.0.0.1020 to be honest (for two different reasons which are not important). But to answer your question, yes BG is completely absent/disabled (Profile 0, No_FVME) so there’s noting to worry about there. Besides, even if it was active at the CSME firmware, the user would need to intentionally activate it by closing the manufacturing mode via "fptw -closemnf". The dumped BIOS also lacks BG entries at FIT, only the Production BIOS is configured that way (which is normal).
That’s not possible as this is a Pre-Production system so only the OEM has access to these internal SPI images. I did notice the 8MB vs 7MB difference.
Why do we need to increase it? The PRE system has an even larger 32MB SPI chip so size is definitely not a problem. The normal way to deal with this is to take the space from the Engine region. That’s what FIT does. All extra space is appended at the end of the Engine region because the BIOS must always be at the end. I’m sending you the old FIT. You can replace the BIOS region within it and re-build the entire SPI image in that way. If you’re talking about UEFITool failing to modify the BIOS, I can’t be of help there. But I don’t think working with the BIOS region only will cause issues at UEFITool. Leave the rest of the SPI rebuilding for FIT.
Obviously it didn’t work and no, the provided Production dump is ok. As I said, your system uses Pre-Production firmware which won’t accept the Production firmware from the Production dump. I’m mostly talking about CSME and PMC firmware which use different RSA Keys at PRD vs PRE PCH so they are inherently incompatible with one another. You can’t take the PRD SPI image and flash it at your system. It will fail immediately because the CSME firmware won’t load and thus won’t allow the CPU to take control and boot further. The goal is to use the PRE CSME and PMC firmware from your dump and then modify the BIOS region to hopefully make it work.