EASY SOLUTION TO NOT DISPLAYING MAX WIP LIMTS
Once you add a certain number of columns to your board, Jira no longer displays the Max WIP limit (Max:4) due to space constraints. It does however display a number in a red box if you go over the Max WIP Limit, demonstrating their is an alternative to displaying "Max:4". Taking the same concept, you could display the Max WIP limit in a green box, then change the box to red when the Max WIP limit is exceeded. You could even change the green box to a green circle so color blind people can tell the difference between when the Max WIP limit is exceeded. When used properly, WIP limits are a critical part of optimizing the flow of work. Not being able to see them is a big problem. You already have the solution, it just needs a little tweak.