Hi Christian,
You say you initialize the app.view.js in index.html. That way you skip the Component.js. If you start with
<script>
new sap.ui.core.ComponentContainer({
name : "sap.ui.demo.myFiori"
}).placeAt("content");
</script>
in your index.html the Component.js will be loaded and init function can be used. In the Component.js you can then add your App.view which load the rest.
Have a look at the following github repository for a great example of using Component.js. This example loads the i18n in the createContent but you can move it also to the init function.
Cheers,
Leo