I know this was already proposed in the past but I'm not really sure what was decided, esp. since Multiboot 2 is seeing little to no activity at all these days.
The idea is to add internationalization support to the Multiboot 2 specification (and to GRUB 2). If this existed in the boot loader, then:
(a) There would be a uniform way to ask all installed OSes to use a certain language.
(b) The boot loader and OS could easily be configured to be consistent.
(c) There would be just a little less duplicated code in the world.
All of the field work has already been done; ISO 639 covers everything from the world's major languages to dialects and even dead languages (e.g., ISO 639-3 covers all known languages); all that is needed is an _optional_ language tag. I did hear an argument that perhaps the introduction of internationalization but no actual translations in GRUB might exclude some people but:
(a) The current situation is actually much worse---there are a lot more people
excluded this way.
(b) If this is not adopted, things can't really be improved, can they? Who's going to write translations if there's not support for that?