Currently the creation and deletion of framework instance libraries is somehow delicate. Some constellation like the creation and subsequent deletion of the same libraries don't work or don't work as expected. The reason for this is that the Settings-Editor accumulates all changes to framework instance libraries and commits them when the Apply or OK buttons are pressed.
A different approach may be helpful here: Create or delete the libraries as soon as a framework instance is added or removed. When the user presses the cancel button, recreate libraries that have been deleted and delete libraries that have been created in this invocation of the Settings editor.
This approach has one negligible side effect: Removing a framework instance and then canceling the change has a reloading effect on the framework instance.