Bruce X
The New Living Translation shows the meaning of Zech 1:12 very clearly for those who have difficulties to understand this verse:
"Upon hearing this, the angel of the LORD prayed this prayer: “O LORD of Heaven’s Armies, for seventy years now you have been angry with Jerusalem and the towns of Judah. How long until you again show mercy to them?”"
The angel asked this two decades after they left Babylon why they are still not being shown mercy. So for the last 70 years until now (20 years after exile) they have not been shown mercy. If they were really 70 years in exile then this would mean 90 years no mercy. This is another hint why they can't have been 70 years in exile
--
The NWT renders this verse more correctly; "So the angel of Jehovah answered and said:"O Jehovah of armies , how long will you yourself not show mercy to Jerusalem and to the cities of Judah, whom you have denounced these seventy years". (emphasis added) Thus the text into English shows that the seventy years was a past event and not a present event awaiting an end. The text and its context along with Zech 7:5 clearly shows a reminder of a past event of the exilic 70 years as agreed by many scholars and commentators.
scholar JW