% arara: xelatex: {shell: on}
\documentclass{article}

\usepackage[main={sr-Cyrl-RS},other={en-GB},date=full]{tex-locale}

\LocaleSupportPackageCase
{\newcommand{\textenglish}[1]{\foreignlanguage{british}{#1}}}% babel
{% polyglossia
  \setmainfont{Liberation Serif}
  \setmonofont{Liberation Mono}
  \newfontfamily\cyrillicfont{Liberation Serif}
  \newfontfamily\cyrillicfonttt{Liberation Mono}
}
{\newcommand{\textenglish}[1]{#1}}% none

\newcount\tmpctr

\newcommand{\test}{%
  \section{\textenglish{Document language} \languagename}
  \subsection{\textenglish{datetime2 commands}}
  \textenglish{\texttt{\string\today}}: \today.
  \textenglish{\texttt{\string\DTMcurrenttime}}: \DTMcurrenttime.
  \subsection{\textenglish{Locale Details}}
  \textenglish{Language:} \CurrentLocaleLanguageNativeName.
  \textenglish{Region:} \CurrentLocaleRegionNativeName.
  \subsection{\textenglish{Dates and Times (Obtained from Java)}}
  \textenglish{Today:} \CurrentLocaleDate.
  \textenglish{Time:} \CurrentLocaleTime.
  \textenglish{First day of the week:}
  \CurrentLocaleStandaloneDayName{\CurrentLocaleFirstDayIndex}
   (\textenglish{index:} \CurrentLocaleFirstDayIndex).
  \textenglish{Current month:}
   \CurrentLocaleStandaloneMonthName{\month}.
  \par
  \textenglish{Days of the week:}%
  \tmpctr=1\relax
  \loop
    \space
    \CurrentLocaleStandaloneDayName
     {\CurrentLocaleDayIndexFromRegion{\tmpctr}}%
    \advance\tmpctr by 1
  \ifnum\tmpctr<8
  \repeat
  .
  \subsection{\textenglish{Numeric}}
  \textenglish{Numeric symbols:} 
   \CurrentLocaleNumericGroupSep\ \textenglish{(group separator)}
   \CurrentLocaleDecimalSep\ \textenglish{(decimal separator)}
   \CurrentLocaleMonetarySep\ \textenglish{(monetary separator)}
   \CurrentLocaleExponent\ \textenglish{(exponent)}
   \CurrentLocalePercent\ \textenglish{(percent)}
   \CurrentLocalePermill\ \textenglish{(per mill).}
  \par
  \textenglish{Uses numeric group separator:
   \CurrentLocaleIfNumericUsesGroup{yes}{no}.}
  \par
  \textenglish{Currency:} \CurrentLocaleCurrency
}

\begin{document}

\test

\end{document}