I just try on my 5.1 tc. I update the files in the mmcblk0p1 partitions. It boot ok in a cold boot but if I do a "sudo reboot", I have a
kernel panic - not syncing : VFS: Unable to mount root fs on unknown-block(1,0)
It's ok when I go back to 5.1 files.
Edit : sorry, my bad. I was using an old cmdline.txt. By the way, I will try the 5.2 version