Hello 71 (BTW, what's your real 1st name?),
Ah yes, I see. Your seat covers are new, the rest is not.
Well, when saying "the raised structure..."
The leather on my seats has the raised texture and pattern that the cognac leather is known for.
... you are certainly referring to the two-tone pattern that the cognac 8006 (interior code 250) has.
Cognac and one dark brown (I believe it must be dark brown 248, see our WIKI) are two-tone leathers (and the corresponding MB-Tex is too, at least for the cognac).
This is the main difference to all other leather colors. The basic color of "cognac" is bamboo 8011 (code 249) or something very close to it (see WIKI again).
Now, all MB leathers of those years have a grain structure imitating the skin's surface of the cattle they were made of. Of course this grain pattern is not exactly natural but was "stamped in" with a tool during the leather tanning/manufacturing process. The natural surface itself is smoother.
Anyway, the basic color of cognac is bamboo or something similar and the top of the grain is "dotted" with a reddish-brown color which makes the cognac unique and so beautiful.
With the years and the use of the cars, this top color of the red dots wears off, especially on the seats were the owner is constantly rubbing on with his pants etc. This is the kind of patina on old MB passenger cars that true aficionados love so much and which can basically never be matched exactly again.
In summary: old cognac wears and ages in a different way than the other leather colors: old cognac changes its appearance more and more towards "bamboo" with increasing age. Having said this, you will certainly understand that it is extremely hard to match old and new cognac to each other.
It "is" theoretically possible (by manually painting, dipping or coarse spraying) the reddish-brown top color to the bamboo base color in order to come as close to the sprinkles as it was when new.
Specialized shops can do that (better or worse), so it's definitely worth to look out for other people's recommendations here. But beware, normal interior shops can not! They can only replace old by new; that is what 98% of all shops do. Renovating is a much, much tougher job here; so it pays off if you are patient with looking for the right one.
As I mentioned, most aficionados "love" old cognac (if it is not cracked at least) and mostly much more than new cognac. There is nothing more "typical and characteristic" than well-aged factory-original leather in a classic Mercedes and well-aged cognac can do that best, better than all the other colors. This is both a blessing and a curse at the same time.
To conclusion, it will be hard to give the old cognac a surface or look again like "new cognac", not completely impossible but tough.
The easier way is to protect it well, take care well of it but to leave it as is ... and if you want to match ... perhaps "optically age" your new cognac seat covers by wiping off some of the sprinkles (alcohol (ethanol) works well...; ask me how I know ...).
But I would always recommend to get a professional do that kind of job.
Oh boy ...
good luck !
I am facing the same problem with my sedan's four headrests.
Best,
Achim