After the fry are born they float around the surface of the water for a day or so, certainly for a few hours. Only the lucky ones who avoid detection will make it down to the grass. In your picture I can see a pregnant Female top left... That surface is bare so my advice is to lay some extra plants on the surface, lots if you can as that is where they will hide. Chances are you may have 1 or 2 that made it into cover but only time will tell when they eventually venture out.
MY experience with Swordtails.... I knew that fry are born often in the very early morning hours. I had 2 drops of fry in the big main tank, both times I had other pregnant females ready to drop too in there. (I had divided my 48" into 2). If I turned on the light to see if there were fry, the females would see them and eat them before I could get a net to rescue them to my little floating breeder tank. So 3rd time, I watched as the Sword got closer in time, moved her to my 10 gallon to get relief from the male. It was covered a good 2 inches deep with surface plants. I had about 60 fry the next morning and was able to remove Mom and let the fry grow out in their 10 gal nursery tank. I can do that because my LFS (local fish store) will take what I bring them and actually pay me if they get to a reasonable size. Good luck. If you have a male, it will start all over again in a month or 2.