Westron (and/or its predecessor "Adûnaic") serve as the Common tongue in Middle-Earth and as with all languages, easily the most "fun" thing to do with them, is taking some words or even a short paragraph and writing Researching words from these languages, let alone translations of full sentences is a chore.

So after finding only very few bits and pieces of vocabulary I started asking myself:

To which extent were these languages established throughout Tolkiens work ? Is it even possible to translate (somewhat) arbitrary sentences; is there any sort of complete collection of all confirmed translations or even some kind of "dictionary" - if not from the man himself, maybe cobbled together from multiple sources by the fandom ?