So, is it pointless to try to compose in Quenya and Sindarin?
No, there is nothing wrong with it per se, and it can certainly be both fun and instructive (even this editor has done so on occasion; see for example this “Quenya” version of the Lord's Prayer). But it must always be borne in mind by composers and readers alike that such compositions are not authentic, and that there is virtually no chance that Tolkien himself would have produced anything like the results of such exercises (thus, compare the previously mentioned translation with Tolkien's own Quenya translation of the Lord's Prayer published in Vinyar Tengwar 43). Such compositions are, essentially, a form of fan fiction. Many people enjoy fan fiction, and there's certainly nothing wrong with that (well, aside from copyright issues, specifically pertaining to the right to create derivative works, but we'll leave that aside for now). But a scholar of Tolkien's languages has no more inherent use for fan compositions than a scholar of Tolkien's writings
