In Editing large amounts of text in Shortcuts, I reference the text added into a textarea element in an HTML page I use Scriptable to display. Scriptabe is passed some text, allows the user to edit it in a large HTML textarea, and then returns the new content at the end.
You could extend the approach used into this for any number of form elements. I actually suggest it could be the basis for a custom web based interface for things in the final section of the post, which I think is exactly what is being suggested here.