Transpose and artifacts

I have 6 audio tracks and need to add backing vocals. Unfortunately the singer can’t quite make the high notes…
If I transpose the audio down by 2 to 3 semitones it introduces some artifacts to the 6 audio tracks. After the backing recording is done, when I transpose back up again will those artifacts be worse or do the 6 audio tracks revert to the original artifact free versions?
Or, is there a better way of doing this? (Cubase 12 Pro)

Transpose them using the direct offline process (DOP=F7) but don’t make the changes permanent. When you’re done trash the processes (there is a little recycle bin icon on DOP) and they will be at original state.
If you’re afraid of messing with the original tracks then just select all tracks and from left pane create a duplicate version to work with. When done revert to the first (original) track version.