No, you dont HAVE to move it, it will do fine there, I tie java ferns to my intake tubes on my filters, hides them well.
what kind of bulb, length and wattage will help. id get a new one rated at 6500K(if you dont have it already) the same length you got, java ferns arent demanding and dont really need ferts to survive, but do to thrive.
substrate matters as well if you get most other plants.
also two of my smaller ferns that I trimmed I tied to the top side of a piece of wood directly infront of the outlet for my canister filter and when the daughters sprout it send them off into the rest of the tank. I got little ones all over the place self anchored.