The Language of names

[Dûrbelethwen]

I brought up the subject of Earendil because I read that the language of the Rohrrim and with a different dialect the Hobbits was a form of Anglo-Saxon and that the Rohrrim were close to what the ansestors of the Numenor were like before the big war at the end of the Simillarion

[Falagar]

Well, Tolkien used Old English as a stand-in for 'real' Rohirric in the books, and we have very few genuine Rohirric-words.

Regarding Nellas; I would think it's Doriathrin, a diaect of Sindarin spoken in (you guessed it) Doriath. The last part, -las, is probably the same as the -las in Legolas meaning leaf. (Legolas being a 'Silvanized' form of Sindarin Laegolas, 'green-leaf'.) The first part may come from neldor, "beech". So perhaps the name means 'beech-leaf'. Or perhaps not.