Renaming Voiceover-file in Timeline

Hi Thorsten, 
I thought you are looking for reusing the AI voices, aren't you?
Although it will appear as 'AI Text-to-Speech #' on the timeline when inserting an AI voice, it will show the first few words of the audio in the Media Library. You can see an example screenshot below.

If you want to reuse the audio, you can simply insert it from the Media Library. It's easy to find the file, as it displays what it says in the Media Library.