I am not sure but would say this - I think it will be difficult to come up with a setup where both the usteriana and the discus will do well.
I have what I refer to as Cryptocoryne sp cf usteriana in several tanks. Perhaps you can see if this is the same as your plants. In the first photo, it is at either end of ta standard 125g tank.
This plant has grown grows very well for me without particular care, just a little Flourish here and there. When happy it is invasive, quickly colonizing a tank if unimpeded, and the very tall leaves if not tamed, they reduce/stop water flow id not trimmed here and there. However, they are beautiful plants.
In my own experience, it does NOT like hot temperatures, such as those needed for happy discus. In my upstairs tanks, the summer, indoor tank water temperature reaches 82 (generally) to 85 (max) some days for several weeks. In the past, Crypt meltdown has occurred big time, and I have had to replant the tanks later from other mother plants. At the same time, my basement tank Crypts did not suffer anything.
By extension, I think it will be difficult to come up with a setup where both the usteriana and the discus will do well. Hopefully others have other experiences. Good luck!
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This is a detail of the left side of the same tank, possibly at a different date.
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