I'm mostly looking for casualtieson the american side, caused by german artillery. Yea i can't find it anywhere. May be unanswerable.
"The artillery accounted for one half of the casualties." http://videoindex.pbs.org/program/chapter.jsp?item_id=7792&chap_id=7 That seems too unbelieveable.
Hitler's Last Gamble Appendix E lists casualties for all units on both sides for the campaign but I have not read the book yet. soon. Perhaps somewhere in the text there is some detail for casualties caused by artillery. You need to be specific on the term 'artillery'. Does this include casualties cased in rear area towns such as Liege from V-bomb attacks?
For a starting point try: Coates, Col. James B. Jr., Wound Ballistics Office of the Surgeon General; Washington DC, 1962