I do have Nymphoides and soft water but I don't have shrimp in that tank. Actually, I do have one shrimp which lives in the Java fern. I think it must have been a shrimplet in some red root floater when I transferred it from the shrimp tank. I've tried catching it to put it back but it goes deep into the Java fern when it sees the net.
I bought two pots of Nymphoides, both are doing well. I just remove the leaf stalks right at the base when they threaten to climb out of the tank. I've also had several daughter plants growing from the leaf stalks, I've planted them in the tank as well, though they are slower to grow than the ones I bought, probably as the bought plants already had good roots while the baby plants need to grow them.
I don't know if this plant prefers soft water, someone who knows more about plants should be able to tell us. But there are several reports of amano shrimps destroying Nymphoides. Plecos and bristlenoses also have a reputation for eating it.