Sorry everyone. I have decided I won't fix this until I play Factorio again, which might not happen. I'm not confident I can do it without creating new bugs. As this has a workaround (setting Coverage to 0), it is possible a fix would make it worse, not better. I am leaving it alone.
Changing map settings without making things worse is difficult since Space Age, and needs to be done by someone who still plays the game. I am going to make it worse.
I recommend replacing this from scratch. The mod was years old when I updated it for 2.0, and I did it in a rush. I felt it was an emergency to help players who started maps incorrectly in 2.0 and needed to fix them. Many of my changes were kludges, and I always intended to rewrite it all.
But it is open source and no one needs my permission to update it.
Most of all, you want to generate UI elements programmatically instead of coding in so many things, in so many different places.
Again, I may rewrite it if I play Factorio again ever. But no one needs to wait for this.