lang argument in quarto chapter yaml header is not taken into account

Bug description

It seems that the lang argument in quarto chapter _metadata.yml or yaml header is not taken into account for pdf output. Only the lang argument in _quarto.yml is taken into account.

Steps to reproduce

Here are the files used to reproduce this bug :

_quarto.yml

project:
  type: book
  
lang: fr

book:
  chapters:
    - index.qmd
    - fr.qmd
    - en.qmd

bibliography: references.bib

filters:
  - section-bibliographies

format:
  html:
    theme: cosmo
  pdf:
    documentclass: scrreprt
    citeproc: false

editor: visual

index.qmd

# Preface {.unnumbered}

en.qmd

---
lang: en
---

# English

[@ethier2020]

fr.qmd

---
lang: fr
---

# French

[@ethier2020]

references.bib

@article{ethier2020,
	title = {Using microphone arrays to investigate microhabitat selection by declining breeding birds},
	author = {Ethier, Jeffrey P. and Wilson, David R.},
	year = {2020},
	month = {07},
	date = {2020-07-01},
	journal = {Ibis},
	pages = {873--884},
	volume = {162},
	number = {3},
	doi = {10.1111/ibi.12785},
	note = {DOI: 10.1111/ibi.12785
MAG ID: 2977097847}
}

Expected behavior

The outputs of these files running quarto render index.qmd must be a html website and pdf file with correct citation, i.e. "and" between authors names for english chapter and "et" between authors names for french chapter.

Actual behavior

The outputs of these files running quarto render index.qmd are a html website with correct citation, i.e. "and" between authors names for english chapter and "et" between authors names for french chapter, and a pdf file with only french formated citations (as lang: fr is specified in _quarto.yml).

Your environment

• IDE: quarto command line
• OS: Debian 12

Quarto check output

Quarto 1.4.549
[✓] Checking versions of quarto binary dependencies...
Pandoc version 3.1.11: OK
Dart Sass version 1.69.5: OK
Deno version 1.37.2: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
Version: 1.4.549
Path: /opt/quarto/bin

[✓] Checking tools....................OK
TinyTeX: (not installed)
Chromium: (not installed)

[✓] Checking LaTeX....................OK
Using: Installation From Path
Path: /usr/bin
Version: 2022

[✓] Checking basic markdown render....OK

[✓] Checking Python 3 installation....OK
Version: 3.11.2
Path: /usr/bin/python3
Jupyter: 4.12.0
Kernels: julia-1.10

  NOTE: No Jupyter kernel for Python found

[✓] Checking R installation...........OK
Version: 4.3.2
Path: /usr/lib/R
LibPaths:
- /home/lucas/R/x86_64-pc-linux-gnu-library/4.3
- /usr/local/lib/R/site-library
- /usr/lib/R/site-library
- /usr/lib/R/library
knitr: 1.45
rmarkdown: 2.25

[✓] Checking Knitr engine render......OK

Start with the supplied _quarto.yml, index.qmd, fr.qmd, and en.qmd files and reproduce the issue with quarto render index.qmd. Trace how chapter-level lang metadata is carried into PDF citation processing, then verify that the English chapter uses “and” while the French chapter uses “et” in the rendered PDF.