I’ve always found creating instrumentals, acapella, and TV versions clunky in Wavelab. I think a great solution would be the ability to assign alt versions to mixes, which would be hidden from the montage. Essentially a new pop out window where you can assign and tag any alt versions across an album to their respective main mixes, with an ability to add automatic name extensions of our choosing. This would not clutter the montage, ensure length matching, make exports easy, and more. So throwing it out there!
I have this on my to-do list, but I don’t know when this will happen.
For me, the somewhat new Bulk File Replacement feature solves this issue. After the main album is approved, it’s easy to populate the montage with files with INST or TV Mix in the name replacing the original full versions.
You can do some fine tuning of the search filter to meet your needs.