Reading a rendering into Latin of a certain piece by Tolkien: 'Tres anuli alborum regibus...' Alborum ('of [the] whites')? How did the translator come to decide 'elven kings' should be 'kings of the white ones'?
A little searching sent me into the depths of reconstructed proto-Indo-European, to a root albho- ('white') which begat both elf (English via Germanic origins) and Latin albus; an article at Lingwë goes further, stating that the Latin word is the direct ancestor of the Germanic, and that elf seems formerly to have denoted a (shimmering) white figure. (Incidentally, the same article notes that the -alf in Gandalf is in fact also elf—that makes 'Gandalf the White' a kind of tautology.)
While I can understand Lalaith's needing to cast around for a suitable word – Wiktionary's pumilio ('dwarf'!) is hardly suitable, and perhaps there was a futher aim of avoiding fairytale connotations – I can't find it satisfactory (though I'm impressed by the resourcefulness), because its effect was to confuse me and pull me up short. But what are the alternatives? Elfus has a certain 'brute force' quality about it (while elf, elvis is too horrible to contemplate), and as a translation from English the result shouldn't have to rely on Tolkien's languages (Quendus? Elda, Eldae?).
Apparently there are historical cases of ælf-based words in Old English being used 'to gloss Latin words for nymphs. Around the eighth century, it appears that Old English had no close equivalent to words for the supernatural, feminine and generally unthreatening nymphs: words for supernatural females denoted martial, monstrous or otherwise dangerous beings, while ælf seems not to have denoted females—at least not with sufficient salience to be used as a gloss for words for nymphs. Glossators instead found ways of altering ælf’s gender in order to create a vernacular word for nymphs.' However, adopting nymphic terminology to refer to elves of any sort would clearly be misleading.
At the moment my best idea is to accept a borrowed elv- root but insert the sort of adjectival suffix found in e.g. Romanus, so as to imply 'elven [one(s)]'. The downside is that this still involves employing a non-Latinate root.