This reference is a doozy
I don't know if the photographer decided to skew the left edge to make it more interesting or if that side of the building it actually turned...Either way that side goes to a different vanishing point.
I agree that 2-D works out better for landscapes and I feel like you captured that well previously. Since the reference is so complex and particular, I think your first attempt works out better because it follows the system you created and looks more sturdy.
If you wanted to go by the reference, I would study the reference more and draw on top of it to understand what's going on. Especially one like this where there are a lot of parts to it and it doesn't follow the rules of 2-point perspective.
Below I compared the converging lines in the image to the ones in the latest drawing. The right half looks nice and pretty accurate. Like I mentioned earlier, the left side is skewed a little in the ref so you'd have to be careful there.
I painted over the rounded structure to show what I meant. I think the curve on the top was a little too extreme so I flattened it a little. Also, the ridges seemed thin and a too close to the structure behind it so I added side planes and made the left edge align with the side of the castle. Lastly, the values were too light on the right so I darkened them. I think the combination of these things can help it look more 3-D.
Hope this helps! It looks like you put a lot of work into this so I wanted to be thorough and help as much as I could.