Which was the lingua franca that time. After that, Latin.
Jesus likely spoke Greek to the Romans, including Pilate.
The reason the inscription was also in Latin is because that was the official government language to be used for a statement by a government official, not because some Latin-speaking followers of Jesus needed to read it in Latin. Those people would have been able to read the Greek inscription.
I mean if it were in vernacular I think so.
It would make a sacred English vs a profane english. A liturgical English seems like a good idea.
It would still be understandable but set aside from common speak.