Thank you for your valuable feedback!
Although, the left icons still need to be there to expand and collapse nodes, rather than the serial number.
I agree that should be obvious indication if specific node can be expanded. For seeing inner nodes or for comment. And of course white arrows we use now is common and solid solution. But I think it is clumsy and heavy in part of visualization.
So my idea, is that we could use serial numbers itself instead of arrows. For example, circle around the number could be indication, that there is something inside. We can click on this number-button to see inner nodes or comment.
In this design layout color circles means inner nodes (orange for if/else, blue for repeat etc) and gray circles means comments. I wasn’t sure about this layout so I didn’t put it in first post.
If you still doesn’t comfortable with this option, can you please describe in more details why?
Similar question about comments. Why exactly my version doesn’t suits you?