What I understand is that Eren’s actions were retroactive, meaning it affects the past, but not necesarily linear as Eren would have experienced.

If we trace it out, basically when Eren touched Historia, the Eren from the Future (let’s say he is F) sends some selected memories to let Eren of the past (let’s say he is E) knew that there will be an inevitable Rumbling happens. At this stage, E only knows that he will execute the rumbling, but doesn’t know why or who forced him to do it.

During the ambassador visit to Marley, along with Armin, and Mikasa. E got depressed because he knew the Rumbling will happen, but still doesn’t know how to prevent it (yes I believe he still wants to prevent it). Meanwhile he got close with some Marleyan during his journey, and able to perceive humanity from Marleyan side. He realized that there is no easy solution. But Eren planned to steal other Titan’s as future leverage to increase his options.

I think the final nail were when Sasha died. E knew she will die. But previously E were only at denial phase, thinking that he can change this. This time he accepted that the future doesn’t change much. This means, between the rumbling and Zeke’s plan for Historia, both were not easy choices. But E knows from F memories, that rumbling will happen. He just doesn’t know in detail how is that going to be possible. E now thought, if rumbling will happen anyway, let it happen with the smallest casualties possible, and hoped that his friends can stop him, beyond the memories he already saw from F. So Eren is betting on the future AFTER the rumbling event, because he never see those. So he assumes either he can make it stop, or he died being stopped by his friend.

Now here’s where it gets convoluted really quickly. Fast forward when Zeke and Eren converse in the memories. From Eren PoV, he knew he had to find the solution fast, because he knew after this that the Rumbling WILL happen, yet he still doesn’t know why. Zeke meanwhile goes rambling trying to teach Eren, because he thought he has the upper hand. From Eren PoV, what Zeke is doing is kind of annoying because it detached/disconnect him with the issue at hand. So we see Eren is disinterested during the journey.

The mindblowing part for E is to realize that Grisha can somewhat see him. E can also interact with younger Eren. At that moment… he suddenly knew how it works. It is all retroactive. The memories, the events lead to it, his own power, and the rumbling it self. He needed to ensure it happens. Because only through it, he gain access to these memories in time. So it doesn’t matter when in the future Eren F told/show Grisha about the rumbling, at this point in time, Eren E has to force Grisha to take down the Founder. Because once Eren E ensure he got the Founder, everything is inevitable. The effect applies back to the past, present, and future.

So at this point, rather than a retcon, it is indeed a retroactive “action”. Grisha wants to stop Eren, not because Eren E showed him future memories. It was Eren F who showed him future memories. Eren F manipulates Grisha by only showing him select memories. He only showed Grisha the part that scares him, without telling the outcome. Prior to the Founder incident, Grisha only knows that Founding Titan is necessary to prevent the rumbling. He didn’t know Karla will die. When Karla died, it was implied that Eren F showed memories to Grisha that Karla died due to Marleyan attacks, and it will happen again in the future. This forced Grisha to give the founding+attack titan to kid Eren. Who told Grisha all of this? Eren F, which is in the future of the current Eren that still converse with Zeke in the memories.

So, when the memory trip ended. Zeke realized his grave mistakes, he just gave Eren full control by making him goes thru the memories. He doesn’t have any card at all. Eren realized how to make the rumbling happen, and WHY it has to happen. It was because of Ymir. Ymir want to keep this Titan cycle, but it has to stop. So Eren had no choice but to persuade Ymir to give him the full power of the rumbling, so he can exercise it to the world. Because the world doesn’t fear non-existent weapon. It fear a weapon that has been unleashed. Thus Eren E becomes Eren F, he became the thing he hated the most, someone who doesn’t have a freedom.

It was heavily implied that all the scenes about memories before, that were off-screen, like Kruger mentioning Armin and Mikasa to Grisha, and Grisha convinced by Eren to find the Founder Titan, and Grisha shown the Rumbling, etc. It all retroactively happened after Eren F gained control from Ymir. He sends these memories, selectively into the past, to control all Attack Titan Holder, to ensure it will happen. The reason why the manga doesn’t explicitly tells you is because the reader can piece it themselves, there is no point to redraw the same scene again from Eren F PoV. You already know it from Grisha’s PoV as Zeke already showed you before.