In a paper by Barrow a table is produced explaining whether certain systems are complete/consistent. The following table is presented:
As I understand, none of these results are proved internally. This would mean, for a formal proof of the results one would have to resort to set theory or something similar. That being said, the way the proofs are formulated seem to resort to "common sense", rather than any formal system.
But if we nonetheless say that the results are proven/provable in set theory, Peano-Axioms (or "arithmetic") are proven to be consistent in set theory. So why are the two question marks presented? Should the answer not be "YES"?