Elves who don't speak Westron

[lindil]

Lothlorien was an amazingly insular society.

I doubt if many wanted to even go to Rivendell. Galadriel had created a little valinor, time moved there so slowly it truly was 3000 or so years behind the rest of the world. I imagine it was for an elf rather addicting.

Recall that Celeborn says to Legolas that that he had been to long sundered from his kin in Thranduil's realm.

So probably very, very few Elves in Lorien knew the CT. Why would they? Compared to any Elven -speech , aduniac and it's later descendant must have seemed harsh and unlovely. if they were going to learn anything it would probably be Quenya! Or try and keep their native Sylvan dialect alive.

Yes they had the time, but few had the need or it would seem the desire. Mortals [and their speech as lindir would say] were not their concern.