There is no contradiction. God changed his mind on something which he has done before:
Exo 32:14 And the LORD repented of the evil which he thought to do unto his people. KJV
Exo 32:14 So the Lord changed His mind about the harm which He said He would do to His people.
NASB
Amos 7:1 Thus the Lord GOD showed me, and behold, He was forming a locust-swarm when the spring crop began to sprout. And behold, the spring crop was after the king's mowing.
2 And it came about, when it had finished eating the vegetation of the land, that I said, "Lord GOD, please pardon! How can Jacob stand, For he is small?"
3 The LORD changed His mind about this. "It shall not be," said the LORD.
4 ¶Thus the Lord GOD showed me, and behold, the Lord GOD was calling to contend with them by fire, and it consumed the great deep and began to consume the farm land.
5 Then I said, "Lord GOD, please stop! How can Jacob stand, for he is small?"
6 The LORD changed His mind about this. "This too shall not be," said the Lord GOD.
7 ¶Thus He showed me, and behold, the Lord was standing by a vertical wall, with a plumb line in His hand.
8 And the LORD said to me, "What do you see, Amos?" And I said, "A plumb line." Then the Lord said, "Behold I am about to put a plumb line In the midst of My people Israel. I will spare them no longer.
Another time God changed his mind was regarding the Israelites and the golden calf. God initially was going to destroy them and make a new nation of people from the descendants of Moses instead but Moses intervened and God changed His mind again and allowed the people of Israel to live.
Daniel never prophesied about a 7 year tribulation to begin with. Jesus was already the Messiah for 3.5 years. The only 3.5 years left is as the Prince to come.
That last 3.5 years will be shortened. The longer the Second Coming does not happen, the shorter that 3.5 years gets. The church is being given more opportunity to bring in the harvest for the elects sake. The church should be faithful always even until the Second Coming. The church should not slack off thinking there is going to be a future 7 years of hardship, and if we do nothing, it will be shortened.
The church will have no influence during the tribulation, because that is when Jesus and all the angels will be on the earth. The church is not on the earth at the same time as the angels.
Prophecy is about God changing His mind after warning of evil to come. The city of Nineveh in Jonah is specifically about that. Had they not repented, God would have followed through. The point is how to reconcile God's foreknowledge with what actually happens. God would have known if Nineveh repented or if Nineveh had not repented.
"Who can tell if God will turn and repent, and turn away from his fierce anger, that we perish not? And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not."
Many claim that there will be a future AC, as if it is already a done deal. The only reason for the AC is if the church quit and gave up. So the church is the only reason for the need of a future AC. It is the church that can repent and turn history around: 2 Chronicles 7:13-15
"If I shut up heaven that there be no rain, or if I command the locusts to devour the land, or if I send pestilence among my people; If my people, which are called by my name, shall humble themselves, and pray, and seek my face, and turn from their wicked ways; then will I hear from heaven, and will forgive their sin, and will heal their land. Now mine eyes shall be open, and mine ears attent unto the prayer that is made in this place."
"And except those days should be shortened, there should no flesh be saved: but for the elect's sake those days shall be shortened."
If my people (the elect) shall humble themselves and pray, and seek my face, and turn from their wicked ways. Jesus gave the church the answer how to shorten the tribulation.
People need to stop expecting the AC, and start expecting a golden harvest. Like Nineveh, the tribulation would not be necessary.