I think I figured out the issue why alternate works but not Clover. With alternate you're using fakeID IntelGFX 0x12345678 without graphics acceleration. But when acceleration was added you get KP, so it means you didn't set the DVMT necessary for HD 520 to load. The alternative would be to use Lilu & IntelGraphicsDVMTFxup. So add this kext to /clover/kext/Other with the files from post #60.
Off topic, you could update the kexts using file from murad3994.zip. Most of the kexts are the same, the ones that are not, you could leave them as is.
See also post #2 and 3 here