It is known that PDF rendering for complex scripts is buggy / yet to be implemented properly.See bug 28206. Tamil WikiSource, Wikinews, Wikibooks currently use Collection extension and has the default link on the portlet as PDF only. Since PDF is buggy, please modify the configuration to display ODT for Tamil wiki projects on the portlet instead of PDF. Community concensus for installing on Tamil Wikipedia(another bug will be filed soon for it) is going on (see URL) and the need to change wikinews was brought up there. I am putting down the possible config changes required as I was not sure of the usage between $wmg and $wg. I am also assuming the mw-render has odf as one of the available output formats.
$wgCollectionPortletFormats = array(
'default' => array( 'rl', ), 'tawikibooks' => array( #'rl' for future use after bug 28206 'odf', ) 'tawikisource' =>array( #'rl' for future use after bug 28206 'odf', ), 'tawikinews' => array( #'rl' for future use after bug 28206 'odf', ),
);