Opencore Installed Big Sur, but want to downgrade to Mojave, but installer won't work now??

Hi All,

tl;dr - opencore installed Big Sur, erased it and tried to install opencore Mojave, but get stuck on opencore trying to load the Mojave (or Catalina) installer at:
18:908 00:103 AAPL: [EB|`LD:OFS] Err(0xE) @ OPEN (System\\Library\\PrelinkedKernels\\immutablekernel.x86legacyap.im4m)

GIGABYTE GB-BXi5-4200

CPU: i5-4200
iGPU: Intel HD 4400
Ethernet: Realtek RTL8111
Drive: Kingston 200S mSATA
RAM: 8GB

Opencore: 7.0.2, debug version of everything, kexts and all

Hopefully someone can help a noob out. I installed Big Sur 11.2 on a GIGABYTE GB-BXi5-4200 and it went super smooth and basically everything worked out of the box that could work. I don't have wifi or bluetooth as it is not supported with my hardware. Post-install I was able to get my video card to properly function as well as all audio features and usb port mapping.

My main goal is to use this as a headless media server using Apple Music/iTunes. It all worked great. The big thing I need is Airplay 2 to properly function for iTunes and the app iTunes Remote on my phone to control the library and push to the speakers I want (I have 4 airport expresses that act like a poor man's Sonos). It was all working just fine inside iTunes, but I could not see my airplay devices via the main computer sound controls, no biggie (apparently this is more of an Apple bug, rather than a hackintosh thing) since I just need iTunes/Apple Music to see all the speakers, which it did. So I decided to upgrade to the latest OS 11.5.2 (mostly just to stay current).

All that went super smooth using the apple update mechanism in system preferences. Unfortunately, that introduced a new Apple "bug" into the system that is widely being talked about in the Apple developers forum. Any Mac that does not have wifi/bluetooth will no longer connect to airplay devices via an ethernet connection (even though iTunes/Apple Music can see them).

I decided to downgrade to Mojave since I really really hate Apple Music (it lost all my album covers for 10,000+ albums) and miss iTunes. I can just leave this media server at 10.14 forever or until my iPhone can no longer connect to my Home Sharing music library. Should be a few years at least.

I created a fresh opencore EFI file using the Dortania guide and made a Mojave installer thumb using a Mojave build downloaded directly from Apple and reformatted my hard drive to APFS and now when I try to run the installer opencore gets stuck in a loop and dies on:

18:516 00:021 OC: Prelinked status - Success

18:775 00:259 AAPL: [EB|#SB:HW] x86legacyap\0

18:790 00:014 AAPL: [EB|#SB:MF] (System\\Library\\PrelinkedKernels\\immutablekernel.x86legacyap.im4m)

18:804 00:014 AAPL: [EB|`LD:LF] FIO: 0, DIR: 1, P: System\\Library\\PrelinkedKernels\\immutablekernel.x86legacyap.im4m, DP: 0

18:908 00:103 AAPL: [EB|`LD:OFS] Err(0xE) @ OPEN (System\\Library\\PrelinkedKernels\\immutablekernel.x86legacyap.im4m)

18:922 00:014 AAPL: [EB|`SB:VK] Err(0xE) @ LD:LF

18:936 00:014 AAPL: [EB|`LD:LKCFFP] Err(0x1A) @ SB:SBVK

18:964 00:027 AAPL: [EB|#WL|6] 0x01 0x41 23 0x0E

18:978 00:014 AAPL: [EB|#REBOOT] 1

18:992 00:014 AAPL: [EB|#LOG:RESET:RECOVERY] 2021-08-28T22:44:13