If the property values can change, then QML needs a NOTIFY signal so it can know when they have changed and update property bindings.
If they can’t change, add CONSTANT to your property declaration, for example:
Q_PROPERTY(QString simplified READ simplified CONSTANT).
In your case, there are set methods, which implies the properties can change, but if they don’t change when they’re being used in your QML, you can get rid of the warnings by marking them as CONSTANT.