Pygmy chain swords will send out runners. Even if you planted one it would eventually fill a whole tank (but it would take forever! Better to start with more, like you did).
H. tripartita 'japan' will also spread. It grows out in vines, and each node will grow roots downwards. Mine likes to travel along the substrate as it grows, and if it grows upwards you can just bury any node where the roots are growing and that will hold it close to the substrate.
With stem plants like the rotala, it won't send out runners, but grow upwards. You can cut the stem tops off and plant them, and the stem top will develop roots, and the rooted bottom will grow new side shoots that will grow upwards.
I wouldn't add any more plants until you make sure that these are growing (I wouldn't add more before flooding, either). I'd let these grow in for a few weeks, flood the tank, let everything transition/grow for a couple more weeks, and then evaluate if you have any more room to stuff things in.