Hello Jason, the Knowledge Document Templates are for the User View of a Knowledge Document, so you can customize the Format of the Document when the User views the Document, (kt_document_view.htmpl). This does not change the Edit view of the Document Content, (detail_kd.htmpl).
The TAGS are the content fields which correspond from the Edit form to the View form, ex.(TAG_TITLE, TAG_SUMMARY, TAG_PROBLEM, etc.) In your test Template you have the TAG_COMMENTS in each field so any Comments added to the document, (which can be added in edit view (document author or user with permission to edit) or user view, (user viewing the document) would show in each field. You can view all the possible TAGS by editing a Document Template or creating a new one->click Edit Detail button->Select TAGS drop down, TAGS names should be self-explanatory to the fields on the Edit Document form.
Hope this helps, please let us know.
Regards,
Richard