Thank you for your studious reply. Jews have preserved the writings - particularly the Torah for thousands of years. If you know anything about Sefer Torah scrolls, you will understand that the Hebrew was preserved - so I believe Yeshua did speak Hebrew in addition to Aramaic. John was a learned man reared in Jewish culture and Torah study, so he, too, would probably know and speak Hebrew. Can’t prove it in this instance, but thinking about it in relation to the “mark”, it causes me to ponder.
The Torah was read then spoken by Jesus in the synagogue (see the part where He taught in the synagogue and read the Isaiah prophecy Luke 4 15-21), so He knew that language.
The listeners would know the language also, and thus by inference, John would have known it.