Do a little research Every language (except some minor ones) have an institute
French has one, Spanish has one, Hebrew has one even Ladino has one. Only english does not
There was plenty of serious books written in yiddish most famously Tevye the Milkman (Fiddler on the roof) by Sholom Alecheim. Issac Bashevis Singer (Yentl) won a Nobel Prize in Literature for writing in Yiddish.
Proper means sentance structure, how to congrugate nouns , verbs etc (English grammar is pretty simple as there are no masculine and feminine congrugation)