I'm no expert.
I've posted in this thread before.
I have not read all the posts in this thread.
I've only owned 4 Harleys: a 2007 Ultra, a 2009 Ultra, a 2013 Road Glide Ultra, and a 2012 CVO Street Glide.
The 2007 rattled really bad, and the fix was a new "cush drive" hub for the rear end, called an IDS. At my expense. Fixed the issue.
The 2009 never rattled.
The 2013 didn't rattle, but my buddy who purchased a 2013 Street Glide (non-CVO) had the rattle. Put in a quart of walmart 75-W-something and it went away.
My 2012 Rattled. I bought it used with less than 5000 miles on it, two years old. I put Valvoline 75Wsomething in it and it got quiet. I'm now running BelRay transmission lube that I purchased at a Harley dealer. Nearly 30,000 rattle free miles.
There is another thing, I do not tighten my belt at tire changes. I've marked my rear fork (swing arm) after adjusting the tension at the first tire change. The belt is always set back to the same place. I learned this from my chain bike days. Chains and sprockets wore out from always taking up the slack just a bit more than needed. Once I got my FJ1100, I started setting the chain by marks on the swing arm, and never needed to replace the chain again.
I'm not saying this is a cure, I'm saying these are relatively painless things to try. As for non-HD lubricants voiding the warranty, we all know that is crap.
I'm just adding this to try to give an alternative to hating your CVO. I really like mine, valve noise and all. My sympathies to all who are having problems.
Ride Safe