JAVA MOSS!! interesting..
While i have been in orchids quite a long time.. i too am an avid aquarist (just broke down 3 dozen tanks this past spring, so down to about 65 aquariums) yeah i am a tank hoarder.....
so I do play a lot with growing many many aquatic plants, emersed and immersed, and some may find it interesting but many of the so called "aquatic plants" grown and sold in aquarium stores, both brick and mortar and on line, are NOT true aquatic plants in that they do not grow 24/7 under water and most will need to be able to send their flower spikes above water to be pollinated. All that being said, there are quite a number of "mosses" that are sold in the aquarium trade, and java moss is just one or sometimes can be sold under that generic name.
I personally have about 20 species of aquatic moss, growing under water and above water... in my greenhouse, i have started a colony of moss in a shallow vessel and over time have it grown up the sides out of water and along the ridge of the dish... I have grown it as a "raft" where i set a portion on top of a cork or floating foam, and it will grow upwards as long as it is kept moist, or at least feet wet. As mentioned above, it does not grow as tight as some of the true terrestrial mosses, (they tend to grow denser and cushiony, with a thick mat underneath made up of dead moss, and the decaying objects they are actually growing on. They need moisture but not as critically as aquatic mosses, because they can handle drying up for short periods and still come back).
That being said I can see where there may be some beneficial use as an addition to some species base. I cannot remember who imparted the idea to me, of taking a failing plant and growing it in live sphagnum moss to help it come back around and for me this worked and i would notice new roots starting in reasonably short order. It is commonly known that there are some mycorrhizal fungi benefits in working with moss and orchids.
I will try to use some of my aquatic mosses, in a small experiment to see if it works as well as or better than my live sphagnum moss..
Any