I had added Grantha support to Emacs in bug#55782, so I don't think this problem should appear anymore.

On Mon, Aug 22, 2022 at 9:33 PM Lars Ingebrigtsen <larsi@gnus.org> wrote:
Ramesh Nedunchezian <rameshnedunchezian@outlook.com> writes:

> I am attaching the Org file and a screenshot of how it is rendered in
> Emacs and gEdit. 
>
> Note that gEdit renders Grantha script with no extra action on my
> part. But Emacs won't render the Grantha script unless I explicitly
> set the font to be used. 

(I'm going through old bug reports that unfortunately weren't resolved
at the time.)

I'm unable to reproduce this in Emacs 29

u+11315, 𑌕

renders fine for me:


Are you still seeing this issue in Emacs 29?