Looking at your site code, I think you may have the data explorer already? If you’re hosted with Discourse on the Business or Enterprise plan the data explorer is included.
If it’s not already enabled, you should be able to do that from this setting:
https://community.graylog.org/admin/site_settings/category/plugins?filter=plugin%3Adiscourse-data-explorer
And once enabled you can find it here:
https://community.graylog.org/admin/plugins/explorer
Hopefully I’m right. 
