Comment by Terr_

To quibble/add-nuance: The words have diverged into a false-friend [0] situation. It looks like the same word, but the correct/standard meaning depends on which language is being used at the time.

If someone is writing English and puts "billion" for 10^12, that's a translation error, much like writing "my grandfather became pregnant when he realized he'd locked the keys inside the car." (Instead of "embarrassed.")

Conversely, if I wrote a French or German sentence and put "billion" for 10^9, then I'd be the one making the translation mistake.

[0] https://en.wikipedia.org/wiki/False_friend