Good question
Grey-elven
Gondolin interpreted as 'Hidden Rock' and
Ondolinde 'Rock of the Music of Water' (High-elven) are noted. The later Fall of Gondolin (in
Unfinished Tales) was at least written after
The Lord of the Rings was completed, but it seemingly never gets far enough to give us the 'updated' actual names!
Quote:
'Here the narrative finally comes to an end, and there remains only some hasty jottings indicating the course of the story. Tuor asked the name of the city, and was told its seven names. (It is notable, and no doubt intentional, that the name Gondolin is never once used in the narrative until the very end (...): always it is called the Hidden Kingdom or the Hidden City).'
Unfinished Tales
Early names from
The Book of Lost Tales are noted too:
1)
Gondolin 'Stone of Song'
2)
Gondobar (in the Gnomish Lexicon 'Gonthobar') 'City of Stone'
3)
Gondothlimbar 'City of the Dwellers in Stone'
4)
Gwarestrin 'Tower of Guard' ('Watchtower')
5)
Gar Thurion 'Secret Place'
6)
Loth 'Flower'
7)
Lothengriol 'Flower that blooms on the plain'
There exist the variants: Gar Furion, Lôs
'a flower and in Eldarissa losse which is a rose (all after the word flower struck through)' and Lósengriol
'flower of the Vale or lily of the valley'.
Later than The Book of Lost Tales, in
Etymologies one finds:
Gondobar, or for example
'Another name of Gondolin Gondost...' or
'... Garthurian = fenced Realm = N Ardholen (which was also applied to Gondolin)' or
'cf. Garth(th)oren 'fenced fort' = Gondolin - distinguish Ardh-thoren = Garthurian.'
There's also
Loth-a-ladwen 'Lily of the Plain' said (back in HME III) to have replaced
Lothengriol (see 'Poems Early Abandoned' and the footnote concerning this form)
There's probably more that could be posted on this. From these we might guess at a list of updated names at least (while considering that JRRT had come to be working in Sindarin or Grey-elven too, as opposed to the very early Gnomish language).