We should require 2 different implementation, each in different enough (so no C/C++ pair) language with each specification.

Because that way we not only get rid of language's smell in how stuff is implemented, but also the act of implementing the spec will quickly show any cases where it looked simple in spec but turns out to be mess implementation wise.

Too much work ? Well, make your spec be tighter and simpler before you burden the rest of programming community with implementing it