At
https://www.zsg.ch/en/fares-schedule...und-trips.html
On the zsg website, it seems to show that passes, GAs etc. ARE valid (as long as the zones and times are correct)--though the 5SFR surcharge still applies.
Particularly on Sundays (when much of Zurich is "closed"), the short day trips are very popular--lots of people!
Thanks, I was referring to the surcharge, have edited to make clear.