Without any context or landscape it looks like it’s moving backwards to me?

This reminds me of oldschool marquee signs. In the old days they would be a frame of light bulbs turning on and off. Nowadays the same motion techniques are typically only seen in smaller LED signs like you might see at convenience stores, over the lotto counter for instance. I’ve observed this a lot and the ones with 3 frames looping really don’t look like a scrolling pattern, more like a slightly unpredictable back and forth. More frames look like more motion. This ↓ is higher resolution than you’re working with, but it shows what I mean as far as what you’re trying to do.

I can’t speak to a programming solution, but from the draw perspective and knowing animation, having more lines or grids as you call them would help. The top stationary line which I think you’re using as a horizon really confounds your goal here. Ditch that and replace it with a 4th on/off line in order and I think that would help some; if you can get 5 or more lines taking turns in the render then I think that will look a lot better than what you have now.