I can confirm that Twitter embeds do not work. The API that returns a tweet's data returns a
404 error instead, meaning it's either been disabled in a particularly abrupt manner or there is an issue related to Twitter's CDN. Time will tell whether it's a
business move, or a temporary outage. I'm leaving a link to a tweet below, which will serve as an indicator on whether their embedding stuff is working. XenForo uses a different method to embed tweets than the one I use in this add-on but they use the same API in the end.
You don't have to do anything, nor there is any tool in the add-on to process old posts. However, old links will not be turned into embedded media. They will remain as text links.
