603 for maglevs, 574.8 for steel rail, set in France in 2007 by a hotted up, modified TGV.
China holds the record for a stock train at 487, set in 2010.
(all per Wikipedia)
It looks like the article might be implying that they will be the fastest trains operating in revenue service when they enter service, but that surely needs to be demonstrated with a production train in revenue service.
Never ask questions you don’t want answers to. Rule 34.