Someone else will have to give the current answer for AA J pax still having access to the SWISS Lounge these days (they used to, but with some codeshares ending this year, Lufthansa ownership and *A connections, I suspect we'd better not hold our collective breaths and continue expecting it much longer.)

Two things I find:

"Lounge Access
Access is valid when traveling on, or connecting to or from, American Airlines Codeshare flights operated by SWISS. Passengers must produce a boarding pass or ticket valid for first class or business class along with their government issued photo identification (i.e. passport).

Access is not allowed for top tier members, but is based on the class of service flown - AA marketed/LX operated." (aa.com)

-and-

"The SWISS lounge at Zurich Airport offers greater customer comfort
The SWISS lounge, only a few steps past the passport control, offer customers even more comfort, calm and practical working facilities than before. They also boast, as something of a centrepiece, probably the longest lounge bar in the airline world, with a length of 28.6 metres, which offers customers a fabulous view out over the airport and its bustling operations.

Lounge visitors can take advantage of many conveniences:

shorter journeys and transfer times, with Passport Control nearby and direct access to the Skymetro
separate quiet area with three relaxation rooms (for passengers holding a first class ticket)
business areas with various workstations
an informal bar with bartender service.
The lounges can be used by following passengers:

Passengers of first and business class
Passengers with Star Gold status (Miles & More HON Circle, Miles & More Senator and members of frequent flyer programmes of other Star Alliance carriers)
Members of Miles & More Frequent Travellers" (swiss.com)