### Bug description

When I run `quarto render` 
- in a website project
- with a project-wide `lang: cs` setting in `quarto.yml`,

I see:

```
[WARNING] Could not load translations for cs
  translations/cs.yaml: YAML parse exception at line 3, column 13:
  mapping values are not allowed in this context
[WARNING] The term Abstract has no translation defined.
```

And the language-relevant elements in the rendered documents are not translated.

_quarto_yml:

```yaml
project:
  type: website

website:
  title: "quarto-title"
  navbar:
    left:
      - href: index.qmd
        text: Home
      - about.qmd

format:
  html:
    theme: cosmo
    lang: cs
    css: styles.css
    toc: true
```

Quarto 1.3.324
MacOS 13.4 beta

Quarto check (I do have R installed, not sure why that check fails.)

```
[✓] Checking versions of quarto binary dependencies...
      Pandoc version 3.1.1: OK
      Dart Sass version 1.55.0: OK
[✓] Checking versions of quarto dependencies......OK
[✓] Checking Quarto installation......OK
      Version: 1.3.324
      Path: /Applications/quarto/bin

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

[✓] Checking Python 3 installation....OK
      Version: 3.11.2
      Path: /opt/homebrew/opt/python@3.11/bin/python3.11
      Jupyter: 5.1.3
      Kernels: python3, ir

(|) Checking Jupyter engine render....0.00s - Debugger warning: It seems that frozen modules are being used, which may
0.00s - make the debugger miss breakpoints. Please pass -Xfrozen_modules=off
0.00s - to python to disable frozen modules.
0.00s - Note: Debugging will proceed. Set PYDEVD_DISABLE_FILE_VALIDATION=1 to disable this validation.
[✓] Checking Jupyter engine render....OK

[✓] Checking R installation...........(None)

      Unable to locate an installed version of R.
      Install R from https://cloud.r-project.org/
```

### Checklist

- [X] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
dragonstyle
2023-04-15T10:45:05Z
petrbouchal
bug upstream triaged-to
v1.4
open
Translation fo `cs` not used - [WARNING] during render
https://github.com/quarto-dev/quarto-cli/issues/5197