I reviewed your recent thread and it appears that the moss is not really established, more of a loose top-dressing. Furthermore, it is on top of the glued on pebbles and the moss will have to be removed in order to properly remove the pebbles.
After all is removed you can then evaluate the soil as you did with your Juniper. You may want to re-pot it now. Tropicals are not nearly as specific in the time of year to re-pot as temperate trees. Do you have any soil left over from the re-potting you did on the Juniper?
Ynot has strong feelings about moss, mine are not so strong but it is certainly not necessary to keep it. You may find it easier to keep moss on a Schefflera than a Juniper. The Schefflera does not require the high light levels a Juniper does and likes high humidity, which may help as well. After the tree is re-potted you can try to establish the moss if you wish by first drying and crumbling it and then sprinkling it over the surface of the soil where it may begin to grow. I find this looks more natural than simply placing moss on top of the soil in sheets.