The issue with JW, who are interested in this subject (most dont care), I was one of them, they think like that:
537 (actaully 539) is a certain date, then the bible says, Jerusalem be devastated for 70 years, so it must be 607.
If secular sources point to something else, then the bible must be right. secular sources are not trustworthy and often needed changing.
What most JW do not know, because it is hidden from the average student of Gods word (through WTS literature only):
1) 537 or 539 in that case, are also based only on secular sources
2) the time span of 70 years can and perhaps does include the time babylon dominated several countires, not limited to jerusalem
3) most important: it is quite a spectacular stretch to calculate from 7 times foretold regarding a pagan king to the time which should elapse til the reestablishment of Gods kingdom. In fact, this dream of Nebu had no further significant prophetic meaning. its just nonsense.