Why does it need yellow? BOLD images don't show yellow legs etc. Description, reproduced here https://xyloryctinemothsofaustralia.blogspot.com/search?q=Xylorycta+leucophanes does not mention yellow only fuscous (= dark gray or grayish brown) As another desc. quoted says "The adults of several shining white species are difficult to distinguish. These include X. leucophanes Low. from western Victoria and south-eastern South Australia, ........ (Common, 1990). " Maybe Common's desc. was what suggested this sp. to me.
I agree its probably Xylorycta genus. but I'm not sure which one of 25 named species several of which are quite plain and silvery white and look similar to this one. X.. leocophanes on iNaturalist and the ALA seems to have yellowish legs, white labial palps with black tips. and blackish antennae. X. leocophanes set specimens on BOLD seem to show a fine black costa near the base of the foreing. I'm not sure from the photos, does your specimen have white labial palps with black tips?
Yes it is best called Xylorycta sp. All white specimens in other genera have different wing etc shape. I don't know where iNat gets some IDs from. The original description says "Anterior and middle legs black, beneath white; posterior tibiae and tarsi pale-greyish-ochreous, slightly infuscated. " so one pair of legs may have yellowish colour. Also "Palpi above white, second joint beneath fuscous, except towards base."