You can choose to run Logic Pro under Rosetta too, even if it's just for testing. (I'm not clear why running one app native and the other not would prevent the Artist Mix from working, but you may be right).
Just select the Logic icon (when Logic is not running) and do Command - I (Get Info). You can opt to run Logic under Rosetta.
https://www.macworld.com/article/338...p-instead.html
Dominic