What is Japanese Super Flower?
The official frost date is May 15th. However, if you don't believe the ground will freeze again and it is on its way to warming up, go ahead and plant at least the lilium and gladiolas. I've already planted a lot of my dahlias and some are leafing. As far as the Elephant Ear is concerned, someone else will have to say how much coolness they can take.
Even if we do get some frost, if you plant the tubers, corms or whatever several inches down, most likely they won't get hit by frost anymore but they can get tipped.
It is your decision to make...I would at least pot them up and get them started. That way, you can bring them in at night if the temps go low again. Plus the longer you wait, the greater your chance of having dead, rotten or dried out bulbs.