The tank does look great still, the balanse does look a bit too overpowering even if it weren’t blocking the light. It is a beautiful plant, you could just keep cutting the oversized leaves off at the base, if you do decide to remove them they have very big root systems so I would just cut all the leaves off and then cut the top off the crown (well where the leaves come out), I don’t think the rotting roots cause any problems, removing them would be very messy, I have tried it with other crypts I wanted to keep. I never grew Cyperus but it looks a great plant in pics and I expect it would work very well in this beautiful tank.