It's all important to remember the nature of "prophetic" works. They were poetic, creative and hyperbolical. A motif like "70 years" was freely utilized without contradiction. When 2 or 3 writers contradict as to the starting and ending terminuses it likely because they understood the "70" to be flexible. I see here arguments for one roughly 70 years to start here and passionate rebuttals of a different starting and ending date. I've tried to show the debate is pointless, there is no way to settle what is not actually a disagreement. The evidence strongly suggests the motif of 70 to be a prophetic trope for a long time, a lifetime.
On a similar vein, the notions of horrible abuse and deprivations in exile are literary, Jeremiah 29 describes their lives as pretty good. And the Jews were to pray for the prosperity of Babylon.
5 “Build houses and settle down; plant gardens and eat what they produce. 6 Marry and have sons and daughters; find wives for your sons and give your daughters in marriage, so that they too may have sons and daughters. Increase in number there; do not decrease. 7 Also, seek the peace and prosperity of the city to which I have carried you into exile. Pray to the Lord for it, because if it prospers, you too will prosper.”
The "desolate" land is again a literary creation reflecting angst about homesickness more than reality. The land continued to be farmed and trade continued to go on as it had before.