"I think a hard problem for visual languages is the sheer physical labor of creating code using drawing tools."

Has anyone tried yet, to build a compiler, that compiles code into visual programming structures - and back?

I know scratch does this in a very limited way(code to scratch), but are there other tools around?

I am not aware of any, except for mine (which is unpublished as of yet, but if I get the website right, that might change by this weekend).