You can find the answers to both of your questions on Wikipedia: https://en.wikipedia.org/wiki/Clanker
> To the extent the author’s point relies on the incorrect definition, it cannot be consistent or correct.
I don't think that a point based on an incorrect definition is automatically inconsistent or itself incorrect. It might be, of course, or it might just be insufficiently justified. And, to the extent that it is a philosophical point rather than a historical one, the truth or falsity of a philosophical claim doesn't depend on whether someone actually said it, or it is a mistranslation of something someone actually said.
> Why is clipboard on every OS/tool I've used single item?
The wonderful Flycut (https://apps.apple.com/us/app/flycut-clipboard-manager/id442...) fixes this on macOS.