I want to export my source blocks from org-mode to pdf through latex with the export backend `engraved`. I installed the package `engraved-faces`, set the variable with `(setq org-latex-src-block-backend 'engraved)` and exported. 

Everything worked as expected until I tried to use some `latex3` code inside a code block. The export ended with some errors and showing unnecessary characters inside the pdf document next to the `latex3` code.

Here a MWE:

```text
#+latex_class: article
#+latex_compiler: lualatex
#+date: \today
#+title: A Great Title
#+author: Mr. Bigfoot
#+language: en-gb

* Testing source code environments

Here comes some verbatim latex code:

#+name: latex-src
#+caption: Ein Latex-Src Block
#+begin_src latex
 \begin{document}
 \setlength{\parindent}{0pt}
 \end{document}
# \seq_new:N \l_lukeflo_seq
#+end_src

#+name: shelltest
#+attr_latex: :options numbers=left
#+begin_src shell
 touch hello_world.txt && echo "Done!"
#+end_src

Here its over.
```

With the `latex3` code commented out, it gives a good result:

[![enter image description here][1]][1]

But as soon as I use the `latex3` code, the output is messed up:

[![enter image description here][2]][2]

The problem seems to be that `engraved` doesn't produce an appropriate latex color definition for the face the `latex3` code is highlighted with in emacs (invoking **C-u C-x =** its `font-latex-sedate-face org-block`). This `face` is missing in the autogenerated list of latex colors in the intermediate `.tex` file. A random example is e.g.:

```latex
\definecolor{EFc}{HTML}{b22222}
\newcommand{\EFc}[1]{\textcolor{EFc}{#1}} % font-lock-comment-face
```

for the `font-lock-comment-face` (there are multiple such lines).

Thus, the question ist: *How can I add custom faces to `engraved` whose color then will be processed correctly during latex export?*

---

**Edit**

The variables in question are `engrave-faces-themes` and `engrave-faces-current-preset-styles`. I tried to add a custom theme to the first one with `(add-to-list 'engrave-faces-themes '(theme-name . [...]))`, where the `[...]` part is just a copy of the default theme extended with the line `(font-latex-sedate-face :short "fl-sedate" :slug "sed" :foreground "#ff8c00")` to process the face `font-latex-sedate-face` which I use for highlighting `latex3` code.

If I check the variable afterwards with <kbd>C</kbd>-<kbd>h</kbd>,<kbd>v</kbd> `engrave-faces-themes`, my custom theme is added. But it can't be usen during latex-export. The error message states: *"Theme theme-name is not found in 'engrave-faces-current-preset-style' or availible Emacs themes"*. Thus, I need to pass the new theme to the `engrave-faces-current-preset-style` or invoke a function which does this. Unfortunatley, I'm not able to understand the whole elisp code in the package file of `engrave-faces` which processes all this stuff.

So, still happy for help.


 [1]: https://i.sstatic.net/4hQdY.png
 [2]: https://i.sstatic.net/VdMyH.png