Hi @Andreas!
The constraint column can be used for hard stops, or the required column (if the constraint is that you need to answer), but it sounds like you only want soft stops and warning messages.
I don’t think there’s an easy way to go to another screen without pressing next – that is how you generally navigate along. You probably can achieve the same thing without a custom prompt just using if statements, notes with the warning, and then using section navigation or goto. The controller options are documented here: ODK-X Survey Controller Actions — ODK-X Docs
If you can describe a bit more about what you are trying to do with this and why that might help us think of other options.