There has been a bug in Pango rendering of Kannada Unicode characters for a long time now. I have filed the bug report about it on GNOME bugzilla. If you are a Linux user using Kannada, please confirm the bug on the above link.

Anyone interested can take up the bug and file a patch for it on the same bugzilla.

Volunteers interested could refer to the previous Indic patches filed by Rahul Bhalerao:
1. http://bugzilla.gnome.org/show_bug.cgi?id=356685
2. http://bugzilla.gnome.org/show_bug.cgi?id=357790
3. http://bugzilla.gnome.org/show_bug.cgi?id=358174
4. http://bugzilla.gnome.org/show_bug.cgi?id=358224