If they go too limp, you may have got an air embolism, try sniping the stem a little higher while it is still under water to be extra sure you don’t get the air embolism again, if they haven’t started to bounce back yet. Also you can cut some of the fingers in half on the big fan leaves, this will reduce the amount of moisture they lose to the air at their leaves pores(stoma).
You need a lot of very fine air bubbles covering the entire bottom area, and you want to make sure the water is not getting too warm, not much at all above 75*F. You also want to completely light proof the rooting area.
You will get two new tops developing at the node below the cut on the mother, in most instances.