AFAIK, while grub 2 supports BiDi text, it doesn't provide more
support for RTL languages. For non-graphical mode, then only
additional support which is needed is aligning text on the right
side so that text will start from the right side of the screen
rather than starting from the left side. It is also needed when
Grub2 is localized in Right-to-Left languages. Almost all text
that is currently left aligned should be right aligned in RTL
languages.
For the graphical mode, it would be nice if a theme can define
text alignment for menu entries. Also, it should be able to put OS
class icons on the right side of a menu entry's text.