I am not a WDC expert and do not have much experience with the "informer" data source, though I will do my best to provide some general information that might resolve the issue. A good way to investigate the issue with the Tableau Desktop WDC would be to use the Tableau WDC simulator to verify the connector is working as expected, information can be found at the following GitHub page: Web Data Connector Home
Additionally, I am including a link to the Tableau Desktop product help guide, Web Data Connector. The WDC help guide has a lot of helpful information in understanding and building a WDC.
I hope this information helps!
I'm actually using the simulator and that has gotten me this far. At first there were errors about not being authorized because it was working through a proxy but we got that sorted out. So far all I can get in the simulator is the field. Once I try to retrieve the data (a list of departments in this test) it returns nothing, no error and never finishes. No indication of what is wrong. That is why I was asking if the data has to be in a JSON format.
The answer to this appears to be yes.