If you’re going to replace regex half-way with UML and expect people to use a graphical editor, why…

If you’re going to replace regex half-way with UML and expect people to use a graphical editor, why not just use real UML and generate regex from it? Anyone who finds your visualization more accessible than regex is already more familiar with UML than with regex, after all, and probably already has a preferred UML editor; anyone who uses a console-based editor (which is to say, a whole lot of serious developers) won’t be able to use this (and will be philosophically unwilling to anyhow).