Just mentioning that currently:
Some deleted rooms, deleted groups of rooms, removed friends and closed DMs still remain in the Discord tree as empty/offline items. On a server that frequently changes things and/or creates temporary rooms for events, this makes a mess.
Rooms and groups of rooms that are restricted to specific roles, are still visible, listed in the tree, and marked as online. The client does not receive activity for these rooms, and I have not risked trying to post a message to one of those. But it's possible the plugin is attempting to send events or queries to these rooms, tripping security checks in the process.
Mute settings stored serverside are not being followed, and chat activity indicators are being displayed in all rooms.
Miranda's useful Ignore function, used to hide entries in the list, doesn't work right for Discord. If I uncheck stuff and then reconnect the protocol, it all comes back and gets checked again. Some of the servers I'm on have a huge list of rooms, most of which I'm not interested in, so hiding them would be helpful. Also, I don't know how the Discord protocol works, but if hiding the rooms would make the client unsubscribe from event notifications for those rooms and reduce realtime traffic, I would be all for it.