Oh man, I have no idea on this one, but Cabinetman well .... as soon as he gets back from the hospital. I am guessing he seen this thread and had a small mental break down, but once the medication kicks in and he calms down, he should be able to help you...:laughing:...just kidding, I would probably put one more in the group of three in the middle and make it four to offset the unevenness making it appear more uniform, would be my guess
edit: looking at this some more, another thing you might consider is to re-saw out the top spline of the two real close together in the middle, and put a spline back in using the same wood as the drawer, basically making invisible, the remaining splines will look much better. Don't know about the cupping, is the bottom floating in a dado, or did you fix it to the bottom, glue and screw. Cabinetman was a professional cabinet maker for many years, he may have a solution for the cupping.