Update / Upsert formatted text by the API

Hi all,
I need to copy rows from one document to another by the API. It works great except that I’ve found now way for upserting/updating formatted text.
For example, if I get a row by the API with parameter “valueFormat=rich”, the result is

**That's a bold text** a list
- Point 1
- Point 2

However, if I try to update/upsert that string, it is not formatted properly.
How can I update/upsert text without loosing the formatting?

I asked the support and they told me to ask here, because this feature is not implemented :slight_smile: :frowning:

Maybe someone knows an undocumented hack? Or someone knows the internally stored format of the markdown, so that I could try the parameter disableParsing of the upsert request?

Thank you very much!