Very beautiful. A very well tended garden and I love how fun it is to poke around the picture and my impression that the tank looks so super deep.
If you're still thinking about the left, it's easy to imagine Blyxa aubertii away from the far left side back there. If you can keep it as under control as you do the B. japonica it might help with the slope plus get it looking even deeper vs the japonica on the right?
I'd love to see what you do as you think about the tank. Are you thinking about thinning out the left entirely? You're a much better scaper than I but fwiw I'm not feeling the rock in the left foreground. I do totally dig the (Fissidens?) mounds in shade in front of the Rotalas and want more! More!