OK, how do you really update the grub2 config file?

[Tom Horsley]

The comment in /boot/grub2/grub.cfg says it was generated
by grub2-mkconfig, but if you run grub2-mkconfig, you
get a file radically different than the one just created
by (for instance) installing a new kernel.

Could the comment perhaps be made a little more explicit?
Give the full command line perhaps?

Differences I see are in things like the definition of the
load_video function, in the titles for the menu entries, etc.