When you create a project, you decide whether to store it in the cloud, or in your web browser.
If you store your project in your web browser, the training data is stored in your browser’s local storage using a technology called IndexedDB.
App Inventor running on your Android device cannot directly access your web browser, and cannot access the IndexedDB internal storage of your web browser.
This means that if you want to be able to update training data from App Inventor, you need to store your project in the cloud.