System drive: Goodram 240GB CL100
Storage: old SATA 3 Hitachi 4TB and Toshiba 2TB
GPU: Palit GTX970 4GB CPU: i3 12100f
Mobo: (returning) MSI B760M-P DDR5RAM: (returning) Kingston Fury Beast 2x8GB
Screen: an old Samsung 32" HD tv
PSU: BanditPower HX460 550W

After switching to CSM Legacy + UEFI it hangs and crashes throwing a BSOD (too fast to read but on POST sometimes showed b1initializelibrary failed 0xc000009a when the W7 logo animation starts. And when I try fixing it with Windows Recovery, it won't find any errors and the keyboard and mouse won't work (I know how to override it but now it's not a problem since I don't feel like reinstalling the system with UEFI w7 just now).

I know I can make an W7 UEFI bootable usb drive. The problem is that there's just too much hassle setting up stuff again starting from system registry (which requires reinstalling certain apps/games including hundreds if not thousands of mods on few games). I'm not sure if just making the Appdata and Documents backup will do the trick. Many config files I edited manually and not sure if it'll still work after format.

As for specs I'm in the middle of returning the mobo and RAM (MSI B760M-P DDR5 got a bent pin + there's a 5sec power on lag before the pc turns on and I never had a problem with the old pc). I'm also returning Kingston Fury Beast 2x8GB which for some reason won't work with XMP 3.0 profile, I couldn't switch to it like it was greyed out). 99% sure I'll stick to i3 12100f. Btw still wonder if It's worth upgrading to DDR5 or DDR4 will be of a better budget/performance value (in some tests I've seen DDR4 being not much worse if not better). It's gonna be a budget pc anyways, I rarely play modern games but rather mod a lot of 10+ years old games which requires a good single core and 12100f is the beast and I'm also into sound design and music production. I don't do a lot of crazy multitasking. Also, won't be upgrading my GTX970 for now since it'd been bottlenecked by my old quad core cpu and wanna see how it gets along on the new unit before I upgrade. I use a 550W PSU.

Could extended kernel or Windows Red Shift mod help somehow? Or should I (if possible) overwrite/paste some custom files into Windows system32/syswow64?

In the past I had a laptop with i7-7700HQ where W10 was already onboard and if I recall, all I had to do was to flash the bios and load the chipset driver to unlock the mouse and keyboard (and maybe make a bootable UEFI image). Easy peasy.

TLDR: the title.