Each field is saved as comment_meta where key is field’s data_name property. We also have some filters available to control data if needed. like:
wpcomments_thumb_height: Controls thumb height being displayed everywhere
wpcomments_thumb_width: Controls thumb width being displayed everywhere
wpcomment_imagethumb[file_url, thumb_url, image_name]: Image thumb url
wpcomment_filelink[file_url, thumb_url, file_name]: File thumb with link
wpcomments_filename: Every filename uploaded
wpcomments_allowed_filetypes: Filetypes handling