Unity’ object and attribute drawers work with SerializedProperty and SerializedProperty works only for things serialized on a UnityEngine.Object directly. The fields of Tasks and Tasks themselves (Actions/Coditions) as well as Nodes and pretty much everything else in NodeCanvas though, are not UnityEngine.Objects nor serialized on a UnityEngine.Object which is essential for better performance. As such SerializedProperty is irrelevant.
The short answer is that it is simply not possible and that is why a custom object/attributes drawers systems was made. I wish it was possible but sadly it’s not due to how Unity’s drawers work.
Gavalakis
