On the journey back home from Uppsala, I stumbled across a nice and helpful website if you're planning to travel by train: zugfinder.net. It lets you search for a specific train (like, say, the EN 346) and shows how much and how often that train was delayed in the past 30 days. That could have been very helpful indeed for my plans!
You can also see what train is where just now, in case you are looking for a specific one.