Does anyone know if there is a converter for .quest files to convert them in to other commons formats ?

Olly

As in other programming languages???
As in Basic, C, or html???
I think that would be beyond most programming languages.

As in being able to convert the .quest file format to z machine, or Glulx, or other text adventure and interactive fiction formats.

No, there is not.

Your best bet, is to learn Quest and the one you want to convert it to and do that...
Just like I am moving from Basic to Quest.

Glulx is an interpreter for Inform. Which is a different programming language for IF.