Change Project Tempo, Not Audio

Cubase
2

I’d probably save a copy of the Project ‘as is’ in case you need to get back.

  1. In the Pool Select all the Audio files & uncheck Musical Mode
  2. In the Pool set the Tempo on all the files to 89 or whatever the original is
  3. Change the Project Tempo to 89
  4. Move the Audio Parts in the Project Window to their desired location
  5. If you intend to later time-stretch Audio make sure to re-enable Musical Mode

Here some additional info on how this kind of stuff works in Cubase.