There a alot of things that fail and can be the reason for the different errors:
So i do not explore for it because it sucks, anything is always wrong since months,
It was not possible to build an stabel fullworking image.
(I build USB-Storage and f2fs inside my kernel)
At the moment i try to build a solution for the special-NAND-bbt-patch-destroy-other-devices problem.
I use minimal images without f2fs and USB-storage support and they are working (but possible that my Flash are defect on a higher position)