I don't know if you sorted this out yet. I'm using an A7R3 on an Arca-Swiss Universalis. There is only about 3mm of clearance between the handgrip on the camera and the front standard when using Canon Lenses. Sony added 5mm of depth to the A7R4 handgrip, so it is no longer compatable with the Universalis and Canon lenses moving forward.
It may be the same issue with the Actus, where older Sony bodies work with Canon lenses, but the newer Sony Bodies have bigger grips. What you may be finding are some older references on the web that say yes and the ones that say no are based on the newer Sony grip.
And can I just say a sarcastic "Thank you" to everyone who complained about the Sony grip being too small, and reuning the party for those who want to use newer Sonys on view cameras.
I don't know if you were referring to me or the OP, but for the record, I am finally moving on from my Actus and my complete outfit will be for sale shortly. I've taken many good photos with it and recommended it to many other photographers, who have likewise taken many good photos with their Actii, but I've decided there are better options for me to pursue going forward.
Because I rarely need or use rear shift and front tilt and swing movements, only rear rise and fall, I have fabricated a camera around the rear standard of my Toyo VX23D medium-format view camera that provides only rear rise / fall movements:
It's compact and lightweight -- a mere 1 lb., 5.9 ounces as shown in the photo above! -- has a generous 10 mm of rear fall and 22 mm of rear rise available, and there is zero chance of any tilt or swing movements being accidentally applied and ruining photos because it doesn't have them ... lol.
Best of all, I didn't have to modify any of the Toyo bits at all, so I can strip away the modifications I made and reassemble the original VX23D view camera in maybe 15 minutes, if / when the need should ever arise.
Although I have the camera setup to use Contax / Yashica lenses, which have an FFD of 45.5 mm, I can reconfigure the camera's lens panel setup slightly so the lens panel is recessed into the standard by 1.5 mm and therefor accommodate Canon EF lenses as well.
The downside of this camera is there is no way I can accommodate the larger grips of the A7RIII and IV, although I think with some custom machine work (which I'll have to farm-out, because I don't have access to machine tools other than my drill press and disk and belt sanders), I believe I can (just barely) accommodate the A7RII's grip.
For now, though, this is a non-issue for me, because my testing confirms that, to my eyes, the A7R performs better for the type of photography I do (late night, low-light, urban and suburban street and alley scenes, captured using long exposures at base ISO) than all of the subsequent generation cameras do hence swapping to one of these cameras won't necessarily be an upgrade for my purposes.
Fortunately, this camera will readily accommodate a Fuji GFX 50R body and its 8.67 mm longer FFD (26.7 mm v. 18 mm for the A7R) and should work well in combination with various medium-format SLR lenses from the film era. As such, this will likely be my upgrade path if/when I decide to resume photographing during daylight hours, where using a medium-format camera isn't the liability it is for my nighttime photography.
Having now successfully completed four shakedown outings with this camera since I completed it last week, I'm confident it's going to serve my needs well, both now and into the future. So much so, in fact, that I've started work on a
second camera based on the VX23D's
front standard, which is ~5 mm thinner than its rear standard. This means I can either accommodate lenses having FFDs as short as ~39 mm or bodies having FFDs longer than Sony's 18 mm, such as the Samsung NX500 body I converted to use for infrared photography.
This second camera is slightly smaller still than the first one, but also slightly heavier and it will have a slightly shorter range of rear rise / fall movements (i.e., 8 mm of rear fall and 21 mm of rear rise.) As of this afternoon, I still need to fabricate a few parts, but I expect to have it up and running by the middle of next week ... cross your fingers for me!