Europe's stunning new train features a world-first trick no others can do

Some debate as to wether it is a world first , with Spain changing gauges for decades.
https://www.stuff.co.nz/travel/experien ... X6muh2t1aE

Two differences: (1) the span of the gauge change (1435mm to 1000mm in Switzerland vs. 1688mm in Spain, or 435mm vs. 233mm, and in "mere seconds" (how many seconds in "mere"?; and (2) a change in floor height at the same time. (Just throw in an "of its kind" and you can make anything unique.)

I'd go with your 2nd thought, i believe the Spanish -french change takes up to an hour, and a lot of manpower

The Tango gauge changes are automatic. This marketing video explains it