I'm not sure how a cam chain tensioner would make a noise. A tensioner that wasn't working would or could cause cam chain noise.
I know you've discussed this before but I don't know what the outcome was.
Have you got or got access to an auto stethoscope. If not a long screwdriver may suffice. Either with the stethoscope or the metal part of the screwdriver rested on the area concerned, have a good listen. The screwdriver handle will need to be next to your ear.
Listen to front and rear cylinders, any difference.
I presume these are spring loaded adjusters? I've never studied them.
Have a good listen and report back. Why aren't the dealers sorting this out?
Sorry if we're covering old ground.
Upt.