Thanks for the responses. Here's my attempt:
'He has dwelt in the West since the days of dawn, and I have dwelt with him years uncounted; for ere the fall of Nargothrond or Gondolin [a very long time ago]
I passed over the mountains [into Beleriand, over Ered Wethrin]
, and together through ages of the world we have fought the long defeat.'
Not perfect obviously, one problem being that if this was the (imagined) meaning, Galadriel had passed into Beleriand before the
founding of Nargothrond and Gondolin. However, the fall of these cities may be more notable to Galadriel as a general historical marker, so to speak, and this is very compressed history. I note also the song of Durin:
'The world was fair, the mountains tall,
In Elder Days before the fall
Of mighty kings in Nargothrond
And Gondolin, who now beyond
The Western Seas have passed away:
The world was fair in Durin's Day.'
I like the idea because it seems (to me) to include that Galadriel met Celeborn after Galadriel crossed the mountains, and then they basically stayed together to fight the long defeat -- the first crossing has Galadriel passing into Beleriand, the second, with Celeborn (over Eredluin), takes them into Eriador and on to Eregion.
Of course I am biased (and this is what led me to my Hithlum thread)
So I invite any and all opinions: acceptable enough? too far of a stretch? don't be shy if you think it needs rending -- or, if you have more alternate suggestions too.