How to extract and edit tempo derived from a warped track?

[pat the dog]

I'm trying to achieve something like the varispeed effect in Logic where I can slow down a song by a percentage so that I can practise playing instrument parts at a slower speed.

I have an imported audio track in my arrangement that I have set as the "Lead" for the song tempo since it's played by a band without a click track and I want to maintain the relative tempo adjustments.

Doing so automatically generates a tempo envelope on the master track based on the spacing of the warp markers in the lead track.
Now I would like to slow down the entire song so that I can practise playing the bass guitar part. But I can no longer adjust the song tempo because it follows the audio track's lead.

Is there any way I can make the automatically generated tempo envelope "editable"? Then I could select all the nodes and drag them up or down to adjust the overall speed of the song, while keeping the feel of the relative tempo changes.

[pottering]

Right-click that Tempo Leader automation in Master and select "Unfollow Tempo Automation", it will turn into a normal red-ish automation (and set the Clip back to Follower)