That is wrong. If you dared deface Roman money you would find yourself in the custody of the local cohort because you defaced an official symbol of the Emperor and the Empire. Remember the Jesus' remarks about who the money belonged to?
In any case, that was not the question. In the above you have physical proof that when Pilate himself designed the local coin of the realm the language he used for the legend was Greek. Thus indicating that historical writing does exist which can be shown to "prove" that Pilate spoke Greek in carrying out his administration, as per Hermann's question.
This was done all over the Empire - which is why I mentioned Egypt. Of course Egypt was ruled by the Ptolemies, who WERE Greek, and the Romans kept the Ptolemaic coinage system that was already in place. But you'll see Egyptian gods on Egyptian coins, British gods (Sulis/Minerva) on British coins, etc. But the official administrative records would still be in Latin.
If you care to puzzle through this very weighty review of a German work in the Bryn Mawr Classical Review (a collection of essays on colonial administrative practices in the Empire), it appears that the local proclamations, inscriptions, etc. were bilingual and that local governors did operate with reference to existing local law. But the structure of the Empire remained Roman and Latin, and internal records (of which few survive) appear to have remained so as well. I imagine that Greek in the east became more and more the language of empire as East and West split, but not as early as 33 A.D.