Font Book reports "serious problems" with Code 2000?
In my experience Font Book warnings rarely have any real consequences.

It's also hard to imagine any issues that could not be easily fixed by just removing the font.  Install it manually in Home/Library/Fonts and see if you find any problems.

To get to Home/Library, hold down the option key while doing Finder > Go.

If your goal is to ensure complete Unicode coverage, I suspect MacOS already has more of this than the very old Code 2000.  To expand coverage beyond what Apple offers, I would recommend the Google Noto fonts and Symbola.

To see what font has a specific character when Apple's Character Viewer is empty, try Fileformat.