There are a lot of fields like that. They were used at one point, but are deprecated now and no longer contain the data you need. I recommend using account history. https://utopian.io/utopian-io/@r351574nc3/tutorial-viewing-steemit-account-history

You will want to

1. iterate through the history for commentoperation.
2. look for json_metadata for each comment
3. Pull tags from json_metadata. Here's an example of json_metadata.

operations: [
    [ "comment",
        {
            "json_metadata": "{ \"tags\": [ \"blog\" ], \"app\": \"steemit/1.0\" }"
        }
    ]
]

Hope that helps.