Currently the QtQuick parts of QmlWeb (all Item and Animation element classes) and the QML engine itself are both in one file, the import statement in QML is ignored. To gain the same modularity like Qt's QML, we need to split them up and load QtQuick as a module using the import statement.
This project is unfortunately no longer maintained. If a new maintainer wants to step up and take care, the project is archived here: https://invent.kde.org/unmaintained/qmlweb You can just clone it in your private namespace on invent.kde.org and if you have started to work on it and fixed/implemented something get it reviewed and the project unarchived. Sorry for the inconveniences.