Yeah don’t bother then, unfortunately it only appends content to the topic when it’s rendered… it doesn’t add it to the database to make it searchable. I think what you’d ultimately need is a custom plugin or a custom script added to Discourse Automation for it to be fully automatic.
Searching by topic ID or including it in a template isn’t a common request, so it’s not something we support out of the box.
I think it’s that regulars here know it’s not a feature we currently have, so we’re trying to support you by figuring out some potential work-arounds.