I am starting to experience with YAML blocks, so that I store as many as possible source-specific Pandoc command line options and variables within the Markdown source file for easier reproducability at a later stage.

Most things which I currently use work file, except one (which is: successfully passing some font features into the LaTeX output).

Here is my complete YAML block:

---
title: Some Document
subtitle:
    - This is a test for using YAML for metadata.
author:
    - name: Some Name
      affiliation: University of Somewhere
    - name: Some Other Name
      affiliation: University of Nowhere
date: 2016-04-10
toc: yes
numbersections: yes
toc-depth: 3
geometry:
    - paperwidth=595pt
    - paperheight=842pt
    - showframe=false
    - showcrop=false
    - hmargin=72pt
    - headsep=54pt
    - top=66pt
    - bottom=78pt
author-meta:  "Some Name, Some GmbH"
subject-meta:  "Knowledge-Based Information Extraction"
title-meta:  "Some Phantasy Title"
pdfstartpage: 2
keywords:  "Essay, Important, Difficult"
fontsize: 12pt
lang: de
mainfont: WeidemannBook
mainfontoptions:  BoldFont=WeidemannStd-Bold.otf, ItalicFont=WeidemannBookItalic.otf, BoldItalicFont=WeidemannStd-BoldItalic.otf, ItalicFeatures=Colour=AA0000, BoldFeatures={Colour=0000AA}, BoldItalicFeatures={Colour=AA00AA}
monofont:  Letter Gothic Std
monofontoptions: [ Scale=0.8, Colour=AA0000, Numbers=Lining, Numbers=SlashedZero, ]
documentclass: scrartcl
header-includes:
...

My problem is with this line:

mainfontoptions:  BoldFont=WeidemannStd-Bold.otf, ItalicFont=WeidemannBookItalic.otf, BoldItalicFont=WeidemannStd-BoldItalic.otf, ItalicFeatures=Colour=AA0000, BoldFeatures={Colour=0000AA}, BoldItalicFeatures={Colour=AA00AA}

In LaTeX the output becomes:

\setmainfont[BoldFont=WeidemannStd-Bold.otf,
  ItalicFont=WeidemannBookItalic.otf, 
  BoldItalicFont=WeidemannStd-BoldItalic.otf,
  ItalicFeatures=\{Colour=AA0000\},
  BoldFeatures=\{Colour=0000AA\},
  BoldItalicFeatures=\{Colour=AA00AA\}]{WeidemannBook}

This does not compile to PDF and gives this error:

! LaTeX error: "kernel/misplaced-equals-sign"
....
LaTeX is attempting to parse some key-value input but found two equals signs not separated by a comma.

If I remove the backslashes which escape the curly braces, like so:

\setmainfont[BoldFont=WeidemannStd-Bold.otf,
  ItalicFont=WeidemannBookItalic.otf,
  BoldItalicFont=WeidemannStd-BoldItalic.otf,
  ItalicFeatures={Colour=AA0000},
  BoldFeatures={Colour=0000AA},
  BoldItalicFeatures={Colour=AA00AA}]{WeidemannBook}

then the code compiles and works as expected — I get different colors for bold, italic and bold-italic text:

How can I get the required curly braces into the LaTeX output un-escaped from setting it up in the YAML block?

Or is there an alternative way to get my wanted main font `*Features` to work?

Thanks, Kurt