Interference? Probably not.

Well. I made a couple shots today that make things clear. It's just shadows.

I put masking tape arrows on the screen that would point to vertical wires and also cast shadows to correlate the prominent shadows with the wires casting them. Took a pic of that once the shadow effect was noticed.

Today was clear, and the effect was not precisely the same because the time was a little earlier. But it was becoming clear that the shadows were from the vertical wires. I took a pic of the screen with the arrows, and the beam and post, and then went on to take some other pics. Turns out the camera focused on things in my back yard instead of on the screen, and the resulting photo is so bad that I am including it here because it is hilarious. The screen is completely invisible, and the arrows are out of focus and floating in space. Hrummmph.

But there are two photos that show the corners of two screens in closeup, and the shadows cast by them. The degree to which the screens are misaligned is surprising. If you count squares, you can see that the "vertical" wires near one corner move over by one square as they move up three. That is a substantial angle. Where that angle prevails, you can see that the shadow from the vertical wire is actually a little downhill from horizontal.

I had planned to color the wires and their shadows, but you can clearly see what is going on in the photos without that.