The thing is, even I hadn't seen the docs before yesterday, but I could intuit through experience working with similar libraries that my ask wasn't that onerous.
The gist of it was to take the JSON representation of an editor and convert it to Markdown. Every popular editor library has an add on or option to export Markdown as well as import Markdown. But on import/export, you then need to almost always write a small transformer for any custom visual elements encoded as text.
Why MD? Because the user is writing a prompt so we need it as MD so it makes sense to transact this data in MD. It just so happens that the library is newish and docs are sparse in some areas. But totally manageable just by looking at the source how to do it.
I can't say for certain where the disconnect is in this whole thing, but to me it felt like "this isn't easy (because the LLM can't do it), so we shouldn't do it this way".