Interesting your point of view. I don't know if I agree that the fact that we already know how many bitcoins there are means that they are not created. But I agree that the word discovered makes more sense in this case.
The main point of the text is to differentiate bitcoin from common 'coins' that are issued for the government, analyzing what you said, if the title were "Are Bitcoins discovered or issued?" would be better.
Many thanks =)