In regards to heavy arty for OKW, NO..
In regards to your 'historic' claim:
Never heard of the hummel, nebelwerfers,or the schwere gustav, the multiple railway guns and their other heavy mortars?
in regards to the nebelwerfers, where do you think the term firestorm came from?
And if history counts here? Hmm let us have 5 t34s to every panther for the same amount of fuel, let us have soviet artillery spam (just the way the soviets liked it), let us have the IS2 mod 1944 one shot tigers, panthers and kingtigers with ease, let us have only one 76mm long barreled sherman with every 3 to 4 other short barrel shermans and the list goes on...
Well a quick google search informs me that the word "firestorm" comes from the late 16th century, so it sure as hell doesn't come from the Wehrmacht.
As for your other claims, you might want to re-read what I wrote. First, it contained the phrase "in the ardennes." The schwere gustav was a too-expensive impractical piece of shit, and it wasn't at the ardennes. You know what else wasn't at the Ardennes? Meaningful quantities of German artillery pieces or ammunition(1). It's pretty easy to achieve radical superiority in artillery when your enemy started with less than half of the pieces that you had, then has to abandon half of those due to lack of ammunition.
Second, yes, obviously balance > history. You may have noted that the first reason I gave was balance related. That doesn't justify actually misrepresenting history in the way that OP proposes.
(1) http://www.history.army.mil/books/wwii/7-8/7-8_25.htm#p656