When adding a QML import that Qt Creator cannot localize, Qt Creator could suggest installing the Qt Online Installer package that features this import.

Example workflow

Say a user loads a Qt Quick project for a Qt version from the Qt Online Installer, but has not all Qt packages installed. In this example, it's 'Qt Sensors':

In this case, the generic advise will most likely just confuse the user. Instead, Qt Creator could suggest the user to install the missing Qt Online Installer package.