Aha that is looking better, glad it has helped!
- Render passes tells Corona when to stop, when you use the Render button (not when you use the Interactive Renderer). With a value of 0, Corona will keep adding more passes until you manually hit stop (so you can watch it until the noise cleans up to a point you are happy with), while I had the scene set to stop after 10 passes as that seemed good enough. I did enable Denoising as well.
- Render selected, this generally should be Disabled, so that everything in the scene renders. As the tooltip notes, with it enabled, it will only render the selected objects (but keep indirect lighting from other objects affecting whatever is rendered). Usually used to "fix" a render by re-rendering one (or a few) objects, without re-rendering the whole scene.
- GI vs AA balance, must have tweaked that back when I did the original scene. If I remember right my thinking was that the AA (anti aliasing) wasn't too critical in this scene, but I wanted any noise in the lighting to clean up faster. Wouldn't be a major player in differences in your render and mine.
- Max Ray Depth, I did raise that as part of messing around with the scene - it controls how many times a ray can bounce, I was curious in terms of the reflection and refraction going on as to whether it made any visible difference. As I recall, it made no difference at all raising it to 50, I just forgot to lower it again! The default of 25 should be fine, and render slightly faster.
- Image Filter, don't think I changed that, or if I did I don't recall. Wouldn't really affect the look of the material, just the overall image sharpness, with a lower value being slightly sharper.
- The missing HDRI comes from a stray unused bitmap in the scene. I had several HDRIs originally for the bottle on the black background (no ground or wall behind it), but before sending the scene over just narrowed it down to use one since there was a ground and wall. The other image Max remembers, but isn't actually being used anyplace so the message can be safely ignored.
Objects with refraction and reflection are hard to render against plain backgrounds, as most of their shape is defined to the eye by the reflection and refraction, and with nothing to reflect / refract, it is hard to make it look good. In photographic studio set ups, white cards, lights (positioned as much for their reflection as for their lighting angle), umbrellas, softboxes, black cards, etc, are used to overcome this. This does mean the shape of the object will play a large part in where to place these elements, or their 'fakes' in this case! Usually you want them placed so that they show up in the edges, for instance I like the right side of the bottle in your image, but the top left side has a bit too much of the card showing, so moving the card causing that would make its refraction nice and "thin" like on the other side of the bottle.
If you are allowed to have something other than a plain background (other objects, etc) then that might make life easier, but depends on what the client wants for the image!