I don't know if they were joking, but at least one person called this.
Honestly, there's no real practical purpose to the grid. It provides no additional useful information. I just think it's more visually interesting with the grid, and assume this being likes providing visuals regardless of how necessary they are.
Granted, there is one piece of information Verres might have found useful, which was the previous "center" of the flow of magic in the area. I say "might have", because given this development, rather than a potentially useful piece of the fixing the clog puzzle, it's BASICALLY been rendered a fun bit of trivia.