It depends where you store your tuning documents. In the dialog in which you create the tuning files, you can choose a location for storing them. If you store them in the On My iPhone > pianoscope folder, they will be deleted if you delete the pianoscope app. But if you choose any custom created folder like On My iPhone > Tuning Files or on iCloud Drive, they will persist even if you delete the app. If you have installed other cloud service apps like Dropbox, Box.com, Google Drive or MS OneDrive, you can also store them in one of their locations.
Tuning documents are just regular files like any other file on iPhone or iPad.
