Can you post a screen grab so we can get some idea of what you’re up against?

Not knowing a lot of the details, you might try a selective color correction on the green screen. Sometimes that’ll give you a little more control. Hawaiki Keyer is fantastic as well. Maybe worth a shot.

Me neither. But it looks like if you needed to resurrect a 7 project, you could now do in current OS’s.

Lots of others unlocked as well – Aperture, iPhoto, and iTunes on macOS Big Sur and macOS Catalina. Xcode 11.7 on macOS Mojave. Final Cut Pro 7, Logic Pro 9, and iWork ’09 on macOS Mojave or macOS High Sierra

Interesting blurb on macintouch.com about new software/hack that allows current Macs to run software EOL’d by Apple. I haven’t tried, but looks interesting…

https://github.com/cormiertyshawn895/Retroactive/releases

Did you try changing the names of the master files adding proxy to their names? Just relink afterwards. I use a free app called something like “namechanger” to batch rename files.

You might look at TrackX from Coremelt. they have great stuff.

Other thing to do is put a square crop on one shot in orig TL, copy it, and paste that formatting on all the clips.

Just reread… I think if you do the duplicate thing above, make the new square project TL a compound clip, and put that compound clip on a 1920 TL it should work.

Not sure if this is what you’re intending, but in the past, I’ve duplicated my project and just changed the format to say, square for social. Some shots needed repo to center, but all else in project stayed same.