That's quite an achievement. I believe they did the trip downhill. Had they done it uphill the amount of electricity required from the catenary would have instantly overloaded it!
The train actually ran from Preda and thru Bergun, Thusus, and over Landwasser Viaduct to Alvaneu - 24.93 kilometer https://www.trains.com/trn/news-rev...ts-record-for-worlds-longest-passenger-train/
You could run a similar working over the Albula Line using the ABe 8/12 Allegra units that come with the Bernina Line
Always one show-stopper. People here including DTG are also interested in real-world railways not just TSC.
More impressive and moving than the train itself was the sheer delight of the hordes of passengers and spectators covering the mountainsides and valley.