Not sure I understand. SQ and NH have lounges but they are not open to *Gs flying international on other *A carriers? Those lounges are not mentioned as exceptions on the *A website, though these other ones are:

We regret that due to space restrictions, Star Alliance Gold members may not access the Senator Lounges in Stuttgart and Paris (CDG) or the Scandinavian Lounge in Bangkok. In Paris (CDG) Star Alliance Gold memebrs may use the LH Frequent Traveller lounge facilities.
In Singapore we offer access to the Singapore Airlines Premium Lounge instead of the Silver Kris Lounge (Raffles Class) and in Sao Paulo and Rio de Janeiro only the VARIG Business Class Lounges give access, as the VARIG First Class Lounges have space limitations.
Customers under 18 years of age can only use the bmi business lounges instead of the bmi diamond club lounges.
United Airlines' Premier Executive and Premier Executive 1K customer and US Airways' Chairman Preferred and Gold Preferred customers have access to U.S. domestic United Red Carpet Club and US Airways Club locations only when they present a ticket or boarding pass for a same-day international flight.

There would be the same lounge access, or lack thereof, for those flying on other *A carriers as there was for you flying on NZ? At what "check-in" point are those written "invitations" given out, and to whom exactly are they given out? Does one ask for such an "invitation" before they fly to PVG or when they are flying out of PVG? Are things different at PEK (and NRT)? Do you know what to expect before you got to PVG, and if so how, or did you only find out when you try to go in?

Flight was only yesterday. NZ uses both Shanghai Airport business and first class lounges located at Gate 17/18. Which one to use is at the airport's discretion as both lounges accommendate a lot other airline passengers. The lounge reception only collects invitations. No need to present Gold card or boarding pass. I guess same invitation will be given to other *G cardholders at NZ check in counters.

Like I said SQ and NH lounges at PVG are not Star Gold lounges. They are only open to passengers boarding SQ or NH flights. And for those non SQ or non NH Star Gold cardholders boarding SQ or NH flights you will have to collect an invitation at SQ or NH check in counters respectively. Same to NZ only they use the airport lounges.

It seems that Xiatong's answers may only apply to lounge access at PVG for those flying SQ or NZ. Anyone know the story at PVG for those flying other *A carriers, in particular UA and ANA? Is lounge access at PVG another "exception," though not one stated on the *A website? (I wouldn't have thought to ask but for this thread.)