In the past, we came across the same situation where we faced issue with the regional font. To fix it we have overridden pdf invoice file and simply changed the default invoice pdf font and it worked for us. Considering that you can try such solution by changing invoice font, maybe it will work for you.
Firstly, you need to add following code to your extension config file.
Available at : app\code\Namespace\Extensinoname\etc\config.xml
<models>
<pdffont>
<class>Namespace_Extension_Model</class>
</pdffont>
<sales>
<rewrite>
<order_pdf_invoice>Namespace_Extension_Model_Order_Pdf_Invoice</order_pdf_invoice>
<order_pdf_items_invoice_default>Namespace_Extension_Model_Order_Pdf_Items_Invoice_Default</order_pdf_items_invoice_default>
</rewrite>
</sales>
</models>After that add TTF font to your root library if needed.
like this : root/lib/font_name.ttf
Once you are done, Lastly you have to implement that font in your 'invoice.php' file.
Available at : app\code\Namespace\Extensinoname\Model\Order\Pdf\Invoice.php
protected function _setFontRegular($object, $size = 6)
{
$font = Zend_Pdf_Font::fontWithPath(Mage::getBaseDir() . '/lib/font_name.ttf');
$object->setFont($font, $size);
return $font;
}
