I think the best translation to English is only really understandable in context. Here's three examples:
- Imagine a conversation with a tourist guide in Japan. The guide says, "What if a train could travel at 200 miles per hour? Well, this is such a train. The Bullet Train."
- Imagine a very picky Aunt. You suggest taking the overnight sleeper train to Rome. And she says, "I could never take such a train!"
What doesn't appear to be quite correct is the use of 'ilyen' as an intensifier in quite the same way as used in English. As in, "such a great train", or "such a good dog!", or "such a [long] day!"
So, though the translation 'such a train' is correct, it is quite specifically meaning 'a train like this', rather than 'this is an amazing train'.
- Imagine a tourist who has only ever travelled by car, he gets on a train abroad and is surprised that the train is swaying so much. "A train is like this," says the guard.
Perhaps "Trains are like this", "All trains are like this" or "Every train is like this", are better translations...but it is not too egregious to say "A train is like this".