Hello @twihno,
it would help to understand your question if you provide an example of what works/doesn’t work.
In math mode, you can go back to code by using #. It’s tricky to use " in math mode, so here are a few examples to help you know what’s possible.
#set text(lang: "de")
"This is a quote".
#quote($a + h$) // quote equation
$#["a + b"]$ // doesn't work
$#"a + b"$ // string variable (no quotes)
$#quote[a + b]$ // quote content in math
$#quote($a + b$)$ // quote math in math
