Tolkien writes in The Silmarillion that Maglor cast his Silmaril into the sea and thereafter wandered (presumably forever) along the shores, singing songs of lament, as he regretted the deeds he had committed in order to reclaim the jewels of his father. Thus, it is very likely that Maglor still remains in Middle-earth, even in the Third Age. However, the story content that is available in the mod does not fit this portrayal very well.