What makes you think Zechariah was talking about the NHNE?
I do that through the guidance of the NT. It quotes Zech about christ pretty extensively and 1st vs 2nd is irrelevant. He already is the King of Zion etc.
2, there is no place in the NT that shows any interest in a Judaistic element or details to the 2nd coming. I'm referring to passages about the coming in Judgement: Rom 2, 8, I Cor 15, Heb 9, 2 Tim 2, Acts 17, and of course the longest 2 Pet 3. They find the restored world in the NHNE, like the end of Isaiah. What are we supposed to do with the end of Isaiah, go through with a scissors and sort out millenial from NHNE? I don't think so. The millenium of Rev 20 has no Judaistic features and fails at the end. The NHNE has a temple and a sun, but they are God and Christ.
Literalism is a primitive and elementary way to read things. How are men supposed to nurse gentiles when men don't lactate? (see late Isaiah).