Glacier Express yes, Bernina Express only to the border
The panoramic trains are where the choice between packs gets made. The Glacier Express runs from Zermatt to St. Moritz without leaving Switzerland, so the Switzerland pack covers the whole ride. The Bernina Express is different: from Chur or St. Moritz it climbs over the Bernina Pass and ends in Tirano, in Italy, and many travellers carry on from there to Lake Como or Milan. This pack stops at the border, so on that route the Europe pack below is the one that keeps working.
The same logic applies at the edges of the country: Geneva with a day in Annecy or Chamonix, Basel with Alsace or the Black Forest, Lake Constance with Lindau or Bregenz. Liechtenstein, a short bus ride from Sargans, also counts as another country, with its own pack. A trip that stays inside Switzerland, from Zurich to Lucerne, Interlaken and Zermatt, is exactly what the Switzerland pack is for.