Köhler Medientechnik

No not that I know of.
You can program custom buttons to select/cycle through modes but it won't show that on a C4 GUI

Note that this is a fair bit of work (though less than Crestron) and you could create sucha  button for yourself and re-use it with different setups as the driver isn't 'bound' to a specific device.
Changing the icons if you want to go for full 'custom' versions each time isn't overly involved either once you get the hang of it.
 
It will NOT go as far as Crestron, but unique setups and feels are possible within Control4, but you lose some of the 'time and money' gain as you're back to spending time onn GUI customization.

Not on remotes. You could possibly do a pop-up stating the surround mode upon change on a T3, or you could create and use an experience button driver (which would show on all graphical interfaces) that has icons (ig you could use the standard symbols for Dolby Pro Cinema, DTS, NEO, Atmos DTS-HD) and set it based on the receiver feed back to have something display. You could then also use that 'button' to give manual selection if desired.

there is no gui customization. That's actually one of the inherent powers of control4 That programmers can't make these god-awful UIs. Control4 always has a consistent experience driven by the driver's proxies

It is a strong and a weak point of contro4.
On one side it'll always look the same.

On the other side you cannot have flooe plans showing open windows, lights, custom stuff like water levels solar and so on....

You can still use experience buttons to control different things in a room (even on the Neeo).  That gives a fair amount of flexibility.

From a user perspective, I'm actually very interested in seeing how the C4 works for us. As comparison, we have a Crestron touch screen that was put in on our initial install.  The dealer used their 'recommended' look and it's been fine but nothing great.  I know we could have customized more but the cost would have been pretty high. So we've lived with it for a lot of years.  We've never added or changed anything because the cost to do so would have been astronomical as well.  We do have a floorplan of the house with our alarm/contact triggers. I think where we'll see the most value of that will be when we're removing Crestron for our new C4 system so the installer can easily identify all of the contacts. Nice to have, not used much.
I actually like the more standardized feel of the C4 system and it sounds like you can do some things that most people would need.  My guess is that if you were to ask people deciding between the two systems if they 'have' to have something via Crestron custom programming or can 'tolerate' a slight difference in accessing the same control/status and then explained the cost difference - most who are considering C4 would probably be ok with less customization/more standardization.
Now, if someone is putting in a $250k system and money is not object, then sure, they'll potentially be less price sensitive and want more customization.  For the $5k-$75k installs, I would think an extra $2-$5k just for a few more custom items might be a little harder to sell. I know it was for me when I wanted a more custom screen in our Crestron system.  I think we paid something crazy just to get the floorplan with the security contacts showing.  Would not have missed it or even thought of it had it not been 'sold' to me as something cool.
Just a suggestion in the most positive of ways - You may have to adjust your perspective as a Crestron programmer and figure out how to communicate the features and benefits of both systems and not focus on the limitations. Most people buying these systems don't really know what they want when it comes to customization so they rely on their dealer/installer to suggest things.  I think the value of C4 even with more standardization is an easy sell if you communicate that the right way to the client.  Whereas Crestron is an easy sell to other clients that really want the customization and are willing to pay for that.  It's all about how you help the client see value based on their needs vs making them feel like they might be missing out on something i.e. more customization. If you can get past that, it will be easy to get your clients past it.  Just like @msgreenf did above - inherent power and consistent - a lot of value to that to a consumer.
There are definitely comprises with C4 - as there are with Crestron - most clients wouldn't even know how to compare them so your guidance will be key to that.