: ...Point taken, but...
: My source was the little english tolkien(ish?)
Westron <-> Quenya, actually. (Westron is the language of the Numenoreans, represented in LotR as English. Quenya is the language of the high-eleves. There's also some Sindarin translations in there too, I believe.)
dictionary
: in the back of the Silmarillion. However, I'm not sure
: if that was the publisher's add-on or if it was
: something that was originally part of it...
: If it is just the publisher's, it might be wrong.
Well, I believe the preface to the appendices specifically states that it's Christopher Tolkien (J.R.R.'s son, who compiled and edited the Silmarillion after his dad died) including lots of other useful information to help the reader out. So it's not J.R.R. himself writing the dictionary there, but it's a limited selection from his notes. For way more information than you ever wanted to know about Tolkien's languages (Quenya, Sindarin, and numerous others) see the Ardalambion, at:
http://www.ardalambion.com/