slide presentation change language of top title - r-markdown

Question

I would like to get Inhalt instead of Contents in the lower left corner of a slide presentation.
I tried
---
title: "Untitled"
author: "Erich Neuwirth"
date: "2022-09-28"
output:
slidy_presentation:
incremental: yes
pandoc_args: [
"--variable=lang:de"
]
---
## R Markdown
When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document.
## Slide with Bullets
- Bullet 1
- Bullet 2
- Bullet 3
but this did not work.

Answer 1

The lower left Contents could be changed to Inhalts using javascript code (sort of Brute-force way)
presentation.Rmd
---
title: "Untitled"
author: "Erich Neuwirth"
date: "2022-09-28"
output:
slidy_presentation:
incremental: yes
includes:
after_body: content-change.html
---
## R Markdown
When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document.
## Slide with Bullets
- Bullet 1
- Bullet 2
- Bullet 3
content-change.html
<script>
window.onload = function(){
var content = document.querySelectorAll(".toolbar a")[1];
content.innerText = "Inhalts";
};
</script>

Answer 2

With this yaml head
---
title: "COVID-19 <br> Mathematische<br> und <br> statistische Analysen"
author: "Erich Neuwirth"
date: "29. September 2022<br><br><br><br><br>Informatiktag 2022"
output:
slidy_presentation:
incremental: yes
includes:
after_body: content-change.html
lang: de
---
everything works file.
lang: de changes titles and similarar things to German. It just does not replace the Content link in the lower left corner.