Amelia should have an option to automatically trash or delete appointments from the database after a set time, to better comply with GDPR rules about retaining user data only as long as necessary.
Also, Amelia should be intergated with WordPress tools for exporting and erasing personal data, again to simplify GDPR processes.
Gravity Forms has both these options, and they make statments on safekeeing of users personal data a lot simpler.