I had some more ideas which could improve the Custom Maps, i hope it is okay to put them here.
Since there is a grid-style node alignment which is super helpful, it would also be nice to toggle a grid view
Also different arrow-styles would be helpful. Personally i liked this from the Plugin Weathermap since the arrow only takes as much space as the edge and therefore allows for more compact designs.
Besides moving the edge text, it would also be helpful to be able to move the edge label so it does not overlap with the edge and is not easy to read
When setting a background image, this does not move/resize in the same way the map is moving/resizing when zooming or grabbing with the mouse
The background image is e.g. useful for visually grouping nodes of a same PoP.