The Lemmy folks were working on adding Discourse compatibility. It’s on my agenda to check in on that.
That means Discourse is sending a Follow but not getting back an Accept from Lemmy.
Currently you can only do this using an environment variable (e.g. set in your app.yml file)
DISCOURSE_ACTIVITY_PUB_DELIVERY_DELAY=0
The title of a topic is already published. It is the name of the collection associated with the topic.
That is how Discourse to Discourse federation, or Discourse to NodeBB, or Discourse to any forum-like platform includes topic titles. Mastodon does not process titles. If we were to put the topic title in the content of the Note as you suggest this would pose problems, e.g. for when content is federated to platforms that support titles.
Fundamentally, the limitation you’re describing is that Mastodon is a micro-blogging platform. We have already added functionality to accomodate that, i.e. the [note][/note] markup to let you target the content you’re federating. If you want to have proper forum-like federation, I’d suggest federating with other Discourse instances.
Yes, there are many Mastodon instances. But there are also many Discourse instances. If a Discourse instance you want to federate with isn’t set up to do so yet, I’d be happy to help them get set up.