Strictly personally, I consider that black and white or monochromatic photography adds more emphasis and character to the images, that is to say, more personality, which sometimes is not achieved with the use of color.

I agree. Moving away from the color, we get a more accurate idea of the object.

1. I like the sepia version more. It echoes the original in tone, but loses distracting colors.

Also, I slightly adjust the horizontality, around 1°, taking as a reference the lower edge of the floor on the left side of the photo.

There is one feature here when leveling the "horizon line".
The picture was taken when the camera was not parallel to the wall of the building. In this case, all horizontal lines will be inclined and they cannot be taken as a guide for leveling.
In these cases, there can be only one landmark - the vertical in the center of the frame. Parallel to this vertical, the nearest vertical of the photo should be oriented.
In your case, it turned out that the house tilted to the left)

In my opinion, there is not enough work on the composition.
The upper line of windows distracts from people, and the left part also draws attention to itself and introduces an imbalance (it seems too heavy)..

For all the above reasons, I took the risky decision to choose this editing work to submit to the contest, without knowing for sure if I made the right decision or not.

In my opinion, you have chosen the right solution :)
I like the format and the chosen composition.
Excessive yellowness of the color variant and reduced "whites" gave a good aging result.