And, you’re probably wise to hold your peace.
However, I took lessons for a few years from a teacher who was VERY heavy on theory. We’d often spend whole lessons just discussing theory. He had a real passion for it. Also, I minored in Music. I realize minoring in music makes me FAR from an omniscient expert in music! But, I have more than just a clue, too!
But, if I were in your situation and the engineer told me to tune to D-G-C-f-a-d, and he referred to it as “Drop-D”, I know myself well enough to know that the words, “That’s not Drop-D. That’s ‘D-Standard’,” would leave my lips before I even realized I was talking!