I have pushed an updated Python patch to my libreelec-7.0 branch (updated by Raybuntu) so that you won't have to remove Python patches when building for aarch64. I will do the same in libreelec-8.0 branch.
For kernel config you can simply create a symlink in linux folder linux.aarch64.conf -> linux.arm.conf so that with every pull/checkout it will link to latest kernel config.
The build issues you are facing seem to be your machine-specific, I didn't push any changes that could break building in that way.
Unfortunately I cannot check building for aarch64 every time as I don't have enough resources to do that - I compile on my laptop and building for different arch requires a whole new build folder that consumes quite a few GBs. That said I try not to do any changes that can break aarch64.