Yes, increasing that setting would fix it, but I can't say what specific setting you would need as it depends on many other details in your cloud and scene configuration. For the same reason I can't really say how much it would impact render time. I suggest if you need to know then you do some tests of smaller crop regions to get some benchmark times with different settings.
Cloud GI Max Ray Depth shouldn't need to be changed, it controls how many additional rays beyond the primary are calculated, so it can make things more accurate, but in practice it has a limited effect in most cases.
Voxel scatter quality has an effect on cloud v3 shading quality, i.e. noise. In most cases it also does not need to be changed.
- Oshyan