API (script and rest) to update macro data in a document

When building macros that use Javascript and in which you could as a user change the data in the UI, it would be interesting to have an easy way to update the macro parameters and content from javascript.

The API would allow to pass the macroname, the occurence of the macro in the page and the new data to update (content and parameters). Thanks to this API the page would be saved with the data updated.