Automatic Horizon Alignment (Take #2)

Greetings, I have previously opened a similar topic and gentlemen helped me to solve it.

Link to discussion (Here is a script that works great for photos with a different background)

Now there is a problem with modification of that script, as new backgrounds were added to the original photos. On which the script can not be applied

I am trying to modify this script for other photos (Different background where there is no difference in brightness between wall and floor)

But in these photos, there is a clear black line between the wall and the floor.

I thought it would be logical to include one "Threshold" correction step in the action (~12 percent). To get a clear black band.

After that, modify the script so that it detects exactly the black line and not the absolute difference in brightness "findFloor".

But due to my poor knowledge of scripting I could not get a working result.

I will be very grateful if you have an opportunity to help me!