I need help on a concrete cose example with connected and non-connected nodes with parent nodes and large labels

[tfc]

Please have a look at this demonstrator: https://jsfiddle.net/16079vsm/1/

This graph contains 2 category parent boxes that each contain 2 nodes.
In one category, the nodes are connected with edges, in the other they are not.
The nodes contain a lot of text.

There are now 4 things in this graph that i would like to clarify.
Some of the things mentioned do not occur always, so please rerun the script multiple times to observe them.

1. The nodes in the not-connected category do always overlap. How can i avoid that?
2. The two category nodes are rendered either overlapping each other or very far away from each other. How can i avoid that?
3. The label of the categories is not printed, but from the docs i don't understand why.
4. No matter how large the node label is, i can only click in the middle of the node in the smaller central area. Is it possible to extend it to the whole label?