Hi, @lo92fr. Welcome to the SmartThings Community!
It’s not about a correct/wrong way of doing it. The thing is that custom capabilities are a special case where only the device integrator has further information on how they work. In this case, Samsung, since those capabilities don’t belong to SmartThings.
So, in case you expose it to users, they could work as expected or not, especially because Samsung devices use the OCF protocol which means they work on the App level (more details here) and we’ve seen in the past that commands that come from the API are not processed as expected by the physical device even when we use standard capabilities in the request.
The above depends on how the device was integrated, sometimes you can also see there are capabilities populated in the app but the values in the API are empty and that’s because the device integrator must expose this information there as well, otherwise, they will be only visible in the app due to how the communication works.
So, this kind of device is a special integration that you should be careful to work with.