The message dialog for the constraint Attribute Rules in ArcGIS Pro currently is very much technical and not likely to be read and understoud by "normal" users.
It would be very helpful, if there was a way to configure how an error message for a attribute rule constraint is presented in AGP. Maybe the following picture can make my point clearer. The mockup on the right is the way, I would like to configure the dialog to be shown in AGP:

Also see the following question for more information:Configurable message dialog for Attribute Rules?