Fisherman: Since the Jews returned to Jerusalem circa 537...
1. As Finkelstein mentions, there is no evidence to support that 2 year adjustment. It is a fudge by Watchtower, to make its numerology work.
2. The Bible clearly indicates 70 years ends when Babylon falls, not when Jews return to Jerusalem: see Jer 25:12.
Fisherman: ...being in captivity 70 years...
Bible does NOT say Jews would be in captivity for 70 years. Watchtower tricks you into thinking the Bible says that. See what Bible actually says at Jer 25: 8-11. Bible says the nations will have to serve the king of Babylon for 70 years (Jer 25:11). That service (and hence the 70 years) had began by the beginning of Jehoakim's reign (see Jer 27:1-6), and Judah had become a vassal state of Babylon. Jeremiah warned that rebelling against Babylon would only make the subjugation worse (Jer 27:8-22). But Jews listened to a false prophet instead (Jer 28), and as a result Jerusalem is destroyed.
If there was any doubt about the 70 years beginning before the fall of Jerusalem, I think that doubt is removed by Jeremiah 29, where a letter is sent to the earlier exiles in Babylon (ex-King Jeconiah and his entourage) by a courier under instruction of King Zedekiah. Zedekiah sending the letter indicates he must have been still alive at that point, and Jerusalem had not fallen. The letter specifically mentions the 70 years (Jer 29:10) and indicates the 70 years are already underway.