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I found a couple of trnslations.   I found some other info which says use heavy cream instead of water.  

DIRECTIONS For HUNTERSCHNITZEL

Cut 400 g fresh mushrooms (or canned ones) in small pieces.
Remove any water if needed.
Fry mushrooms in 2 tbsp butter or oil.
Add 250 ml heavy cream, stir in content of 1 bag.
Bring to  boil and cook for 1 min.
Place 3 meat slices (pork, veal or chicken) into a  fire proof form, add
the sauce mix on top.
Bake for 30 min on 200 C or 400F. The meat should be tender.



Knorr Fix Jäger-Schnitzel: The Schnitzel classic: Fresh mushrooms, bacon,
onions and parsley composed to a spicy-flavoured sauce.
Without flavour-enhancing additives and without colourings. Quick and easy
preparation.
	

Preparation for: 3 pork, turkey or veal steaks (150 g each) and 250 g
mushrooms (fresh or canned) 
1) Fry the schnitzel in a little hot oil, remove and keep warm. 
2) Clean the mushrooms, cut them into slices (or drain them) and fry them
briefly in dripping. 
3) Add 250 ml heavy cream and stir in the contents of the bag. Bring to the
boil while stirring and cook for 1 minute. Add the schnitzel and let it heat
up in the sauce. Tip: The Knorr chefs recommend French fries for this.
    Here you receive 4 packs of Knorr Fix Jäger-Schnitzel.