I was able to swap my spare slave cylinder with another at O'Reilly that included the clip, and then my wife and I installed it. Works WAY better. Male fitting is snugly all the way in. Hopefully that fixes my issues. I do have the clutch masters option here in case it ends up being necessary in the end... but I think I am going to make the other Alero AWD...
I think I found the clunk:
https://youtube.com/shorts/CFdsruFxaAc
Remember how I said it sounds very similar to when I used to not use brake pad anti-rattle clips and the pads would shift in the caliper during braking? Looks like the pads are able to move in this setup too.
With brief Googling, I found this thread.
https://www.ctsvowners.com/threads/c...brakes.161184/
Just pads shifting, no big deal. These Power Stop calipers seem to have a few quirks. Probably should've gotten new OEM or something. Oh well don't really care a long as it's not a function or safety concern. Only happens when braking hard.