Appendices sidebar section title is not localizable (hardcoded "Appendices")

[tiger-graphics]

Description

When using a Quarto book project with appendices: defined in _quarto.yml, the sidebar automatically creates a grouped section titled "Appendices".

However, this label is not affected by:

• format.html.lang
• format.html.language
• language: options (e.g. appendix-title, appendix-ref)
• crossref: options

As a result, even in fully localized (e.g. German) book projects, the sidebar still displays the English title "Appendices".

Minimal Example

project:
  type: book

book:
  chapters:
    - index.qmd
    - chapter1.qmd

  appendices:
    - appendix-a.qmd

format:
  html:
    lang: de
    language:
      appendix-title: "Anhang"
      appendix-ref: "Anhang"

Observed Behavior

• Cross-references correctly use “Anhang A”
• Appendix headings in the document are localized
• The sidebar still shows the section title "Appendices"

Expected Behavior

The sidebar section title should:

• Either follow language.appendix-title
• Or be configurable via a dedicated option
• Or be derived from the document language

Current Workaround

Since the custom sidebar options are limited in book projects, I currently copied the _language.yml file from the quarto installation to the quarto project directory (parallel to quarto.yml) and adapt the entries in _language.yml to show the desired words.

section-title-appendices: "Anhang"

Environment

Tested with Quarto 1.8.27 as local user installation on OpenSuSE 15.6 with de-DE localization.

[mcanouil]

I believe your issue is that you've place lang under html for some reason.
This means you did not want it to apply at project level and only at page level, thus the sidebar do not get your lang.
Scoping options has a meaning.

As of the current 1.9, the sidebar is localised.

• create project book i14087
• echo lang: de >> _quarto.yml
• quarto render

Please change the category of the discussion to Q&A.

[tiger-graphics]

Thanks a lot.
This really works.
I never dared before placing the 'lang' statement above/before the project definition.
Again: Many thanks