LilyPond - "Table of Contents" TOC in different languages

Question

I am working on a music-book using LilyPond with different languages (here English and German). I created a minimal working example (MWE) referring to a snippet that can be found here in the LilyPond Documentary. This is what I made:

\version "2.20.0"

\paper { indent = #0 }

#(define-markup-command (toc-line layout props label text)
  (symbol? markup?)
  (interpret-markup layout props
   (markup #:fill-line (text #:page-ref label "8" "?"))))

%Inhaltsverzeichnis
\label #'Inh
\markup {
  \column {
    \large \fill-line { \null \bold "Inhaltsverzeichnis" \null }
    \toc-line #'Inh "Inhaltsverzeichnis"
    \toc-line #'ersterTeil "Erster Teil"
    \toc-line #'zweiterTeil "Zweiter Teil"
    \toc-line #'dritterTeil "Dritter Teil"
    \toc-line #'vierterTeil "Vierter Teil"
    \toc-line #'fünfterTeil "Fünfter Teil"
    \toc-line #'sechsterTeil "Sechster Teil"
  }
 }

\markup {  \vspace #1 }

%Table of Contens
\label #'toc
\markup {
  \column {
    \large \fill-line { \null \bold \italic "Table Of Contents" \null }
    \toc-line #'toc "Table Of Contents"
    \toc-line #'firstPart "First Part"
    \toc-line #'secondPart "Second Part"
    \toc-line #'thirdPart "Third Part"
    \toc-line #'fourthPart "Fourth Part"
    \toc-line #'fifthPart "Fifth Part"
    \toc-line #'sixthPart "Sixth Part"
  }
}

\markup {  \vspace #1 }

\label #'ersterTeil
\label #'firstPart
\score { \relative c' { c4 d e f g1 } \header { piece = "Erster Teil - First Part"}}

\label #'zweiterTeil
\label #'secondPart
\score { \relative c' { d4 f g d c1 }\header { piece = "Zweiter Teil -  Second Part"}}

\label #'dritterTeil
\label #'thirdPart
\score { \relative c' { e4 f g e c1 }\header { piece = "Dritter Teil - Third Part"}}

\label #'vierterTeil
\label #'fourthPart
\score { \relative c' { c8( d e f) c( d e d c1) }\header { piece = "Vierter Teil - Fourth Part"}}

\label #'fünfterTeil
\label #'fifthPart
\score { \relative c' { f8 g f g e4 d c1 }\header { piece = "Sechster Teil - Sixth Part"}}

\label #'sechsterTeil
\label #'sixthPart
\score { \relative c' { c4( g' f d c1) }\header { piece = "Siebter Teil -  Seventh Part"}}

%...

For some reasons I would like to apply a different approach, that can be found in the appropriate section of the LilyPond Documentory for "Table of Contents", basically suggesting the preconfigured commands \table-of-contents and \tocItem in a way like this:

\markuplist \table-of-contents
\pageBreak

\tocItem \markup "Erste Partitur"
\score {
  {
    c'4  % ...
    \tocItem \markup "Ein bestimmter Punkt innerhalb der ersten Partitur"
    d'4  % ...
  }
}

\tocItem \markup "zweite Partitur"
\score {
  {
    e'4 % ...
  }
}

Does anyone know how I can use this approach with a similar outcome as in my example, getting two tables with two different languages?

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The Project can be found here on GitHub.com