Hello,
About:
This error means the Webhook Secret Key option value in WP-Discourse doesn’t match the password defined in your Discourse webhook. Can you check it?
@simon will correct me if I’m wrong, but yes, a WP post needs to be synced to a Discourse topic. For existing topics, you should have the option to link to an existing Discourse topic:
Once synced, the comments should be retrieved.
I’m not sure if there is a better way; hopefully, some can provide better insights.