I think the entire series is bad if I understand it correctly. I ask the same question again: are some files inaccessible with current code but become accessible with these patches? Aka can I create a file that I can't read with grub-fstest in the current code?
GRUB2 follows strict design that same full file name refers to the same file and doesn't have some hidden state. It's possible to add some state outside of disk drivers like having an analog of relative paths or handling it on script level but the fs drivers are definitely not the right place to patch up the difference between mount-based unix model and full path model used in GRUB.