I changed at Cluj on my way to Sighisoara 7 years ago, and I see these days there is a day train (0810 from Cluj, 200km) that takes 3h20m and gives you the afternoon there - returns at 1849.
It's a magnificent medieval town of Saxon origin on a hill, little changed for centuries.
My trip* was bedevilled by engineering works on the line, but I think they are now finished, and they have started on the line west to Oradea (and Budapest).
The public areas at stations are nicely modernised, but beware broken platforms, steps and seats, also passengers cheerfully crossing live tracks to reach trains.
*I ended up on a stopper (42 stops) that took 6 hours, consisting of an electric loco and 2 battered coaches.
One of the most interesting train journeys I've ever done!
The line was under serious reconstruction at the time.