Let's continue the discussion from the players group here.
At a glance, I had some real trouble figuring it out, since the color of the block of the player to your right is your color. So the colors don't match (I know they shouldn't...) but I'm wondering if using simple iconography would be easier? Like, a small square on the RHS of your board matches up to the small square on the LHS of the person to your right? Circles, triangles, etc.?
I like the idea but I agree with deaconbluz that it's still confusing. A slight tweak might help, though. Instead of a solid color, a striped strip with both the color of the court and the adjacent player would probably be cleaner visually. With that continuity players could quickly look for the striped strip that matches the edge of their court to find the adjacent player.
I will try something on the studio environment with the colors and share screenshots here. Unfortunately with the current setup icons will probably not work as there is not enough space. It would mean only three cards would fit in a row on mobile screens. In the end I might also add game settings so it's customisable.Striped strip (or similar) would be even better.