[Mithalwen]

Well there are limited possibilities here aren't there. At this point. There ar known Elf settlememts: Lorien, Mirkwood, Mithlond, Rivendell. Boromir's difficulty in locating Imladris would seem to rule it out.so apart from Lorien there are two possible options. We know that the people of Thranduil had dealings with the men of Laketown and probably also with the woodmen in Rhovanion. The Dorwinion wine indicates there was trade with otherwise undocumented communities further afield. Not impossible that there was some low level of contact between Gondor and Laketown and through that elves. Or while elves may not have gone to Belfalas it maybe that men sailed north to Mithlond. Much easier to find the gulf of Lune than a hidden valley . Final possibility is that the visitors to the Palantir in the Emyn Beraid were not the only wandering companies. Eomer's query to the three hunters might suggest there were sightings of Elvish folk in Rohan.