Have there been many engine problems with the 2017 Buick Cascada?

Hello, air seals? Sometimes, concerns do require a more skilled, qualified technician to work with the manufacturer in a diagnostic process. This is not in any way indicative of you discovering further problems -- rather it is usually the case when something abnormal has occurred that needs troubleshooting -- more than a "pattern" failure people see all the time. I would say that as long as the vehicle is working now, all should be good!