for calls in a workflow, in the UI, each is under a "show/hide" status in the UI. Furthermore, under each call, the inputs and outputs are also under a "show/hide"
If a task is marked "Failed" I think that upon navigating to the workflow with the task, maybe the calls should be "Shown" (not hidden) by default. That way, finding problems takes less time.
Also, perhaps there could be a button "Show All" and/or a corresponding "Hide All" to reveal things too. This button could possibly help in finding problems too.
-eddie