The Rotala in my bowl is quite red and Hygrophila is pink, and I'm using just a cheap desk lamp with a "warm white" LED bulb, no special aquarium light.
The second photo shows Rotala and Ludwigia. Yes, Rotala is really this red IRL. This is just a quick mobile shoot, not photoshopped at all. Ludwigia looks very green when viewed from above, the red shows mostly on the undersides of the leaves.
Amazing plants, they look really nice.
Do you know what the water column NO3(nitrate) readings are for your setup?
You said it's a Walstad setup, meaning capped soil.
Rotala rotundifolia is something that has thrown me through a loop trying to get it to turn anything but green (at this point I'm convincing myself that buceplant sent me rotala rotundifolia 'green' that was just yellow when I got it because it was emersed grown
The consensus is to have low no3 readings, but then I've seen some in higher no3 water column readings that aren't green.
Most, if not all the examples I've seen have had some type of soil setup, but including your example the light levels only determine how red it gets.
OP, low-energy plants that turn a different color than green: Ludwigia super red, Crypt Wendtii 'tropica'.
You could try your luck with some Rotala H'ra and see what happens, same with ludwigia Arcuata, but there's no guarantee it'll be anything but green.