Alterações no formato da data devido a strings personalizadas

Question

Eu adicionei bibstrings personalizados e usei o idioma ngerman. Se eu deixar a definição de ngermanbefore bibstrings em branco, ele imprimirá o formato da data conforme desejado. DD.MM.AAAA

No entanto, se eu usar LanguageMapping ngermanou german, ele aparecerá como DD/MM/AAAA - por que isso acontece e qual é a maneira correta de exibir o formato correto?

Arquivo LBX:

\ProvidesFile{custombibstrings.lbx}[2019 SoSe]
\DeclareBibliographyStrings{%
  inherit      = {ngerman},
  andothers    = {{et al\adddot}{et al\adddot}},
  byeditor     = {{herausgegeben von}{hg\adddotspace von}},
  bytranslator = {{übersetzt von} {{\"u}bers\adddotspace von}},
  editor       = {{Herausgeber}{Hg\adddot}},
  editors      = {{Herausgeber}{Hg\adddot}},
  urlseen      = {{letzter Abruf}{letzter Abruf}},
  paragraph    = {{Paragraph}{\S}},
  subparagraph = {{Absatz}{Abs\adddot}},
  article      = {{Artikel}{Art\adddot}},
  bydirector   = {{unter der Regie von}{unter der Regie von}},
  byproducer   = {{produziert von}{produziert von}},
  volume       = {{Vol\adddot}{Vol\adddot}},
  seriesseason = {{Staffel}{Staffel}},
  episode      = {{Episode}{Episode}},
  duration     = {{Spieldauer}{Spieldauer}},
  fsk          = {{FSK}{FSK}},
}

MWE

% arara: lualatex: { shell: true, synctex: true }
% arara: biber
% arara: lualatex: { shell: true, synctex: true }
\RequirePackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@online{Amano.2011,
 author = {Amano, Fumiko},
 title = {Testimonial Videos of Survivors},
 url = {https://www.global-peace.go.jp/OTHER/ot_german_pic_syousai.php?gbID=920&dt=161012173049},
 date = {2011-11-18},
 urldate = {2019-08-23},
 maintitle = {National Peace Memorial Halls for the Atomic Bomb Victims in Hiroshima and Nagasaki},
 organization = {{Net-Gtas Global Network}},
 keywords = {primary}
}
\end{filecontents*}
\documentclass[
  12pt,
  a4paper,
  headings=standardclasses,
  listof=totoc,
  numbers=noenddot
]{scrartcl}

\usepackage{showframe}
\usepackage[left=2.50cm, right=2.50cm, top=2.50cm, bottom=2.00cm, footskip=1cm]{geometry}
\usepackage[onehalfspacing]{setspace}
\usepackage[main=ngerman, english]{babel}
\usepackage[babel, german=quotes]{csquotes}
\usepackage[ngerman]{isodate}
\usepackage[ngerman]{datetime}

\usepackage[match,MogaHMinEx90]{luatexja-preset}
\setmainjfont{MogaHMinEx90}
\usepackage{luatexja-ruby}
\ltjsetparameter{jacharrange={-3}} %    punctuation is Latin

\usepackage[
  backend=biber,
  style=ext-authoryear,
  sorting=nyvt,
  datamodel=customstyles,
  maxnames=25,
  innamebeforetitle=true,
  usetranslator=true,
  alldates=terse,
  labeldate=year,
  dashed=false,
  isbn=false
]{biblatex}
\addbibresource{\jobname.bib}
\usepackage[hidelinks, pdfencoding=auto]{hyperref}
\begin{filecontents}{customstyles.dbx}
\DeclareDatamodelEntrytypes{video}
\DeclareDatamodelFields[type=field,datatype=literal]{
  duration,
  format,
  type,
}
\DeclareDatamodelFields[type=list,datatype=name]{
  director,
  producer,
}
\DeclareDatamodelFields[type=field, datatype=verbatim]{
  fsk,
  seriesseason,
  episode,
}
\DeclareDatamodelEntryfields[video]{
  duration,
  director,
  episode,
  format,
  fsk,
  producer,
  seriesseason,
  type,
}
\end{filecontents}
% regarded in custombibstrings
\NewBibliographyString{bydirector,duration,episode,format,fsk,paragraph,subparagraph,article,byproducer,seriesseason}
\DeclareLanguageMapping{german}{custombibstrings}

\DeclareSourcemap{
  \maps[datatype=bibtex]{
    \map[overwrite=false]{
      \pertype{article}
      \step[fieldsource=entrysubtype, match=\regexp{\Anewspaper\Z}, final]
      \step[fieldsource=journal, final]
      \step[fieldset=author, origfieldval, final]
      \step[fieldsource=author, match=\regexp{\A(.*)\Z}, replace=\regexp{\{$1\}}]
      \step[fieldset=author+an, fieldvalue={1=journalauthor}]
      \step[fieldset=options, fieldvalue={journalauthor}]
    }
  }
}

% smallcaps
\newtoggle{bbx@journalauthor}
\DeclareEntryOption[boolean]{journalauthor}[true]{%
\settoggle{bbx@journalauthor}{#1}}

\renewcommand{\mkbibnamefamily}[1]{%
  \ifitemannotation{journalauthor}
    {\mkbibemph{#1}}
    {\textsc{#1}}}

\newtoggle{bbx@director}
\DeclareEntryOption[boolean]{director}[true]{%
\settoggle{bbx@director}{#1}}

\renewcommand{\mkbibnamefamily}[1]{%
  \ifitemannotation{director}
    {\mkbibemph{#1}}
    {\textsc{#1}}}

\newtoggle{bbx@producer}
\DeclareEntryOption[boolean]{producer}[true]{%
\settoggle{bbx@producer}{#1}}

\renewcommand{\mkbibnamefamily}[1]{%
  \ifitemannotation{producer}
    {\mkbibemph{#1}}
    {\textsc{#1}}}    

\DeclareDelimFormat[bib]{nametitledelim}{\addcolon\space}

% editor in parentheses
\DeclareDelimFormat{editortypedelim}{\addspace} 
\DeclareFieldFormat{editortype}{\mkbibparens{#1}}
\DeclareDelimAlias{translatortypedelim}{editortypedelim}
\DeclareFieldAlias{translatortype}{editortype}

\DeclareFieldFormat
  [article,inbook,incollection,inproceedings,patent,online]
  {title}{#1\isdot}
\DeclareFieldFormat
  [thesis,unpublished]
  {title}{\mkbibemph{#1}\isdot} % thesis title italic

% no period after addon titles
\renewcommand*{\titleaddonpunct}{\addspace}
\DeclareFieldFormat{titleaddon}{\mkbibbrackets{#1}}
\DeclareFieldAlias{booktitleaddon}{titleaddon}
\DeclareFieldAlias{maintitleaddon}{titleaddon}
\DeclareFieldAlias{journaltitleaddon}{titleaddon}
\DeclareFieldAlias{lawtitleaddon}{titleaddon}
\DeclareFieldAlias{subtitleaddon}{titleaddon}

\newbibmacro{online:editor+maintitle}{% organization in front of maintitle
  \printlist{organization}%
  \clearlist{organization}%
  \setunit*{\addcolon\space}%
  \printnames{editor}%
  \setunit*{\addcolon\space}%
  \usebibmacro{maintitle}}

\usepackage{xpatch}
\xpatchbibdriver{online}
  {\usebibmacro{byeditor+others}}
  {\usebibmacro{online:editor+maintitle}}
  {}{}
\xpatchbibmacro{editorstrg}{\bibstring}{\bibcpstring}{}{}
\xpatchbibmacro{editorstrg}{\bibstring}{\bibcpstring}{}{}

\renewbibmacro*{in:}{%
  \iftoggle{bbx@journalauthor}
    {}
    {\printtext{%
     \bibstring{in}\intitlepunct}}}

\DeclareNameAlias{ineditor}{sortname}

\renewcommand*{\volnumdelim}{\addcomma\space}

% set online sources as per IOA
\renewbibmacro*{addendum+pubstate}{%
  \setunit{\space}%
  \printfield{addendum}%
  \newunit\newblock
  \printfield{pubstate}}

 \DeclareListFormat[online,law]{organization}{% organization in caps 
  \textsc{%
    \usebibmacro{list:delim}{#1}%
    #1\isdot
    \usebibmacro{list:andothers}}} 

\urlstyle{same}% 
\DeclareFieldFormat{url}{\url{#1}}
\DeclareFieldFormat{urldate}{\mkbibparens{\bibstring{urlseen}\addcolon\space#1}}


%----------------------------------------------------------------------------
%   CITING
%----------------------------------------------------------------------------
\makeatletter 
\renewbibmacro*{cite:labeldate+extradate}{%
  \iffieldundef{labelyear}
    {}
    {\printtext[extblx@inner\blx@delimcontext delims]{%
       \printtext[bibhyperref]{%
         \iftoggle{bbx@journalauthor}
           {\printfield{issue}%
            \setunit{\addcomma\space}%
            \printtext[\blx@delimcontext labeldate]{%
              \printdateextra}}
           {\printtext[\blx@delimcontext labeldate]{%
              \printlabeldateextra}}}}}}
\makeatother

\renewcommand\postnotedelim{\addcolon\addspace}
\DeclareFieldFormat{postnote}{\mknormrange{#1}}
\DeclareFieldFormat{multipostnote}{\mknormrange{#1}}

%----------------------------------------------------------------------------
%   MAIN
%----------------------------------------------------------------------------
\begin{document}
\nocite{*} 
\printbibliography[heading=bibintoc,title={Literaturverzeichnis}]
\end{document}

Answer 1

Um .lbxarquivo deve sempre conter definições para pelo menos duas coisas.

1. A bibliografiacordas(com \DeclareBibliographyStrings)
2. e a bibliografiaextras(principalmente manipulação de datas, formato para ordinais, etc. com \DeclareBibliographyExtras).

.lbxAtualmente falta no arquivo uma definição para os extras da bibliografia. Meu biblatexaté reclama disso no.log

Package biblatex Warning: Using fallback definition for \mkbibdateshort.
(biblatex)                The command should be defined in the .lbx file.
(biblatex)                If you see this message, the .lbx file could not be
(biblatex)                loaded, is faulty or does not contain a definition
(biblatex)                for \mkbibdateshort.


Package biblatex Warning: Using fallback definition for \mkbibdateshort.
(biblatex)                The command should be defined in the .lbx file.
(biblatex)                If you see this message, the .lbx file could not be
(biblatex)                loaded, is faulty or does not contain a definition
(biblatex)                for \mkbibdateshort.

---

Como você basicamente escreve um novo .lbxarquivo, você precisará herdar os extras da bibliografia de outro idioma ou definir todos os comandos necessários do zero. No seu caso, herdar de ngermanwith \InheritBibliographyExtras{ngerman}parece a melhor opção. Você ainda pode substituir as definições por um arquivo \DeclareBibliographyExtras.

A situação é semelhante com as strings de bibliografia, mas aí a herança é fornecida pelo par chave-valor especial inherit = {ngerman},em \DeclareBibliographyStrings.

Eu sugiro fortemente que você faça um favor a si mesmo e adicione o nome do idioma ao nome do arquivo genérico custombibstrings.lbxpara torná-lo legível custombibstrings-ngerman.lbx(é claro, se você puder criar um nome mais descritivo do que custombibstringsisso também pode ser útil...)

\ProvidesFile{custombibstrings-ngerman.lbx}[2019 SoSe]

\InheritBibliographyExtras{ngerman}

\DeclareBibliographyStrings{%
  inherit      = {ngerman},
  andothers    = {{et al\adddot}{et al\adddot}},
  byeditor     = {{herausgegeben von}{hg\adddotspace von}},
  bytranslator = {{übersetzt von} {übers\adddotspace von}},
  editor       = {{Herausgeber}{Hg\adddot}},
  editors      = {{Herausgeber}{Hg\adddot}},
  urlseen      = {{letzter Abruf}{letzter Abruf}},
  paragraph    = {{Paragraph}{\S}},
  subparagraph = {{Absatz}{Abs\adddot}},
  article      = {{Artikel}{Art\adddot}},
  bydirector   = {{unter der Regie von}{unter der Regie von}},
  byproducer   = {{produziert von}{produziert von}},
  volume       = {{Vol\adddot}{Vol\adddot}},
  seriesseason = {{Staffel}{Staffel}},
  episode      = {{Episode}{Episode}},
  duration     = {{Spieldauer}{Spieldauer}},
  fsk          = {{FSK}{FSK}},
}

Naturalmente você precisará

\DeclareLanguageMapping{ngerman}{custombibstrings-ngerman}

Com este arquivo e esta linha alterada, o MWE produz

editarAlterado {\"u}bers\adddotspace vonpara übers\adddotspace von.