Your tank is stunning! I am just starting my planted tanks and can't wait until they are gron in and I have to trim. I'm sure my fish can't wait either
Here is what I found far as your question regarding your hygro corymbosa:
Propagation can be done by doing some pruning of the lateral shoots which readily form along the stem.
Select a side shoot with several nodes and cut off a 4-inch length of the shoot with clean sharp scissors.
Bury the cut ends of the shoots in the substrate. You can use a piece of bogwood or a rock to keep the cuttings in place. You can also do the same thing by pruning and replanting the top portion of the stem. But, keep in mind the pruned, rooted portion will become bushier and bushier after performing repeated trimmings this way.
Also make sure to remove any leaves that would otherwise get burried in the substrate when you are placing the cutting in it's new home.