Am I missing something? Are we talking about the same lens?
Yes, you are. And No, we're not...
There have been several different families of lenses labeled "Contax" over the years. The 35/f3.5 lens you reference is part of the Contax 645 family and it was designed to be used with their (still wonderful after all these years) Contax 645 body.
Unfortunately, similar to the Contax N lens family, it uses electronic aperture control, hence the need for the various smart adapters and/or workaround methods to change the aperture when it's used as an adapted lens with other camera bodies.
Cambo offers a modification service that replaces the electronic aperture control mechanism with a mechanical one and remounts the optical elements into a new body that is attached to a dedicated Cambo Actus lens panel.
Unless you replace the Actus lens panel with a Contax 645 bayonet, this means it can only be used with a Cambo Actus or Ultima camera.
Cambo calls this modified lens the "Actar 35." Their modification service costs $1,075 and the buyer must also provide a donor lens:
https://www.cambo.com/en/actus-series/actus-g-view-camera/actar-35-retrofit/
I have no first-hand experience with the Cambo modifications, but I do have a Contax 645 35/f3.5 lens and have used it with both my Contax 645/P30+ outfit, as well as an adapted lens on my various FrankenKameras, with great results. Although the cost of having Cambo modify it is not inexpensive, it's not unreasonably high, either.
If I was in the position of needing a 35 mm lens to use with a GFX body and a Cambo Actus or Ultima camera, I would seriously consider having mine modified accordingly.