CSQuotes not working properly

Question

I am editing a text that has a few articles in Devanagari and the rest in English. The opening and closing quotation marks are not displayed correctly. I have gone through most of the discussion on this site, but the problem persists.

\documentclass[paper=17cm:24cm,11pt,DIV=12,BCOR=10mm,headinclude=true,pagesize=false,headings=small,table]{scrbook}
\usepackage[frame,a4,center]{crop}

\usepackage{xspace}

\usepackage{hyperref}
\usepackage{csquotes}
\usepackage{newunicodechar}

\addtokomafont{disposition}{\rmfamily}
\renewcommand{\sffamily}{\rmfamily}

\usepackage{xunicode}
\usepackage{fontspec}
\usepackage[osf]{libertine}

\usepackage{polyglossia}
\XeTeXlinebreaklocale "zh"
\XeTeXlinebreakskip = 0pt plus 1pt minus 0.1pt

\setdefaultlanguage[variant=uk]{english}
\setmainfont{Linux Libertine O}
\newfontfamily\ef{Linux Libertine O}
\setotherlanguage{sanskrit}
\newfontfamily\devanagarifont[Script=Devanagari,Mapping=devanagarinumerals]{Sanskrit2003}
\font\df="Sanskrit 2003:script=devanagari" at 12pt
\font\dfs="Sanskrit 2003:script=devanagari" at 10pt
\setotherlanguage{tibetan}
\newfontfamily\tf {Kailasa}
\newfontfamily\stsong{STSong}
\newcommand\chinese[1]{{\stsong #1}}
\begin{document}

\df {अधुना कवेः कुलनाम विमर्शितव्यम्~। अत्र विद्येते द्वौ पाठौ ``उदुम्बरनामान" इति ``डम्बरनामान" इति च~।}


\ef {In a way, we can say that ``Jain poetics" is not given proper attention in the entire history of Sanskrit poetics on which scholars of the rank of Mahāmahopādhyāya Kane }

\end{document}

Answer 1

There are three main obstacles for csquotes in the code shown in the question

1. The code loads csquotes but then does not use it. It still 'hard-codes' the quotation marks with

   ``Jain poetics"
   

   You want to use csquotes facilities like \enquote

   \enquote{Jain poetics}
   

2. csquotes only adapts to language changes, not to font changes. Currently the code just switches font with \df, but not language. You want to try something like

   \begin{document}
   \begin{sanskrit}
    अधुना कवेः कुलनाम विमर्शितव्यम्~। अत्र विद्येते द्वौ पाठौ
    \enquote{उदुम्बरनामान} इति \enquote{डम्बरनामान} इति च~।
   \end{sanskrit}
   
   In a way, we can say that \enquote{Jain poetics} is not given proper attention
   in the entire history of Sanskrit poetics on which scholars
   of the rank of Mahāmahopādhyāya Kane
   \end{document}
   

   But you will also need to use the csquotes option autostyle for csquote to adapt to all language changes in your document.

3. csquotes does not have a configuration for Sanskrit quotation marks. So you have to supply one yourself. I couldn't find something when I googled for Sanskrit quotation marks, so you will have to fill in the correct characters yourself in

   \DeclareQuoteStyle{sanskrit}
     {<outer left>}
     {<outer right>}
     {<inner left>}
     {<inner right>}
   

   Note that your Sanskrit font must contain the characters you use. That was a problem in the code from the question as well: Your Sanskrit font doesn't have the characters for `` and ", so you just get empty boxes.

In total, here is what the code could look like (but you need to adjust the \DeclareQuoteStyle{sanskrit})

\documentclass{article}
\usepackage{fontspec}
\usepackage[osf]{libertine}
\usepackage{polyglossia}
\usepackage[autostyle=true]{csquotes}
\usepackage{hyperref}

\setdefaultlanguage[variant=uk]{english}

\setotherlanguage{sanskrit}
\newfontfamily\devanagarifont[Script=Devanagari,Mapping=devanagarinumerals]
  {NotoSansDevanagari-Regular.ttf}

\DeclareQuoteStyle{sanskrit}
  {<outer left>}
  {<outer right>}
  {<inner left>}
  {<inner right>}

\begin{document}
\begin{sanskrit}
 अधुना कवेः कुलनाम विमर्शितव्यम्~। अत्र विद्येते द्वौ पाठौ
 \enquote{उदुम्बरनामान} इति \enquote{डम्बरनामान} इति च~।
\end{sanskrit}

In a way, we can say that \enquote{Jain poetics} is not given proper attention
in the entire history of Sanskrit poetics on which scholars
of the rank of Mahāmahopādhyāya Kane
\end{document}