https://bugzilla.redhat.com/show_bug.cgi?id=1659748
--- Comment #41 from Mike FABIAN mfabian@redhat.com ---
Expected result ගෝර්ඩ්න් Actual result in emacs ර්ඩ්න් (see attached image)
It seems to be working in GNU Emacs 27.0.50.
The problem still exists in GNU Emacs 26.3 (which the version of Emacs in Fedora 31).
GNU Emacs recently changed upstream to using harfbuzz, maybe that fixed it.