Congregation Adath Jeshurun was created in 1906.
Since you don't give any details of where you know this word from, and in what language it is, I'll try to tell you what I know and hope that's what you wanted. I know of a Hebrew word "Adah" (pronounced "Eidah"), which means "Congregation" (usually in a religious context). It can also mean a group of people from the same place or practising the same customs - religious or otherwise. The "th" at the end of the word is grammatical, and is used whenever there is a noun after the term "Adath", like in "Congregation Shalo'm", which would be "Adath Shalo'm", or any other name, whatever the name of that particular congregation is.
Elie Wiesel is still alive today, and is still working to educate people of all ages on the Holocaust, and how we need to learn from history.
J.D. Salinger is not considered a Transcendentalist. He is more commonly associated with the genre of realist fiction, focusing on themes of alienation and authenticity in his works. Transcendentalism was a philosophical and literary movement in the 19th century, while Salinger's most famous works, such as "The Catcher in the Rye," were published in the mid-20th century.