I'd like to (optionally) see an arrow direction on edges. Most of the graphs I work with are directional. If I drag to try and create a back edge, it doesn't seem to care about direction and just assumes everything is left->right.
It is a very nice tool with a lot of potential. At the moment I use tools like https://dreampuf.github.io/GraphvizOnline, knotend just adds the missing gui for editing with drag/drop and easy keyboard interaction. With arrow rendering as option and some basic way of styling (changing the background color is good enough for me, to distinguish different types of nodes) this can become my default tool for documenting flows.
The dot file import and svg/dot file/mermaid export as very useful for creating flows, including the svg/mermaid in documentation files and using the dot file for archiving / future changes.