Backup import failed due to special characters German Umlaut ä ü ö

I try to rename an application.

My first attempt to create an empty application with the new name and import the backup file failed due to the error message there exists already an application.

My second attempt was to download the backup and change in the xml files the application name which worked except for everything related to special characters like German Umlaut ä ö ü. All Elements: Dimension, Folders, forms etc. with special characters where not imported.

My current solution is to manually rename all elements which is a lot of effort. Is there any better solution?

How can we import snapshots with special characters?