Very nice. But instead of demanding the user write three different kinds of code I wonder if having a more accessible 4GL or GUI editor of some sort could be a better option..

By "three different kinds of code" are you referring to the Domain, Substance, and Style DSLs of the original Penrose? Just to clarify, Bloom is an alternative to those DSLs, only requiring you to write in one language (JavaScript, or TypeScript if you prefer).