One of the great features of huginn is the diagram. That's where there are green and red indicators. Red indicates both errors and when a longer than expected period has passed. This makes quickly inspecting your workflows easy.
Sorry. I meant running an agent on a machine that is separate from the machine running huginn. The machine running the agent is not accessible publicly but has internet access (doesn't accept connections but can initiate them). huginn would be accessible publicly.
Retrieving data from huginn can be done with the DataOutputAgent.
Sending data to huginn can be achieved through the WebhookAgent.