Ran a windows registry error fixer 5 times, each time it says there are only 512 errors. I don't know if it is failing to delete them, or hitting some type of self imposed RAM limit...

Also half of the comments on Cnet say they think it's pretty good, and half say it's spam ware, but I haven't seen any ads. (average 4.5/5)

Anyone know if "Windows Registry Repair" actually works?

At least what I *heard* is the fact that in general most registry cleaners don't do much useful stuff apart from getting rid of some unused registry values (usually from uninstalled applications) as well as occasionally giving spam and downright screwing with your registry... As I said, this is just what I heard, not personal experience
Concerning your problem, I would bet it's failing to delete them

I use CCleaner only it doesn't remove all unused but does remove those from newly installed software especially after installing visual studio 😓