Hi there=
The Brunswick medal rolls are partially extant )in fact probably completely extant). I would recommend you contact John Franklin via the 1815 web page- Project Hougoment. All sorts of odds things have been popping up over the past year (like French Imperial Guard medal rolls) and certainly there are Brunswick rosters out there. Alas, I do not have them.
I am hoping to garnish the Nassau and Hanoverian rolls when I go have a look at the Cumberland Hussars' court martial records in Wiesbaden next month.
Thanks to the Hanovarian Military History Society, we now know that all Hussars were awarded the medal. with the probable exception of Colonel Hake.