Shantanu,
That seems like a weird way of adding a TN document type. Normally it’s done using TN Console. If you’re replicating DocType from one TN server to another, it’s also easier to just export/import from TN Console.
What you’ve ran into is type definition discrepancy between TN and IS. Check the results from wm.tn.doctype:list against that from wm.tn.doctype:view. Aside from the big differences in the number of fields returned (which aren’t needed for wm.tn.doctype:add), note the different definitions for fields like “Deleted?”. Unfortunately this is a common theme in TN’s handling of Boolean values. Unless you really have a reason for adding a TN DocType programmatically, I’d suggest just go the easy route and using TN Console.