Sorry, but I can't see the relevance of that; standard operating height, for fighter sweeps, was 20,000'+, and no European mountain comes within 4,000' of that, so all fighters found the need to climb at some stage (just after crossing the enemy coast, in 1941-4, in the RAF's case.) No fighter Squadron is going to go in at low level, unless they're on a strafing/bombing run, and they would expect to have high top cover, somewhere above.
And yet when you take off at München, Bavaria and fly any direction other than north, you'll have to make 12000 in about 12000 from the airfield. Mountains kind of go up sharply. Airfields among them. It's like that from Bavaria to the Black Sea. Know why they called Poland's Pripet Marshes unpassable? Because south is all mountain, swamps in the middle, you have to go north along the Baltic.
England isn't Europe mate, it's off in the north sea somewhere. I told you that you guys only see the low countries when you look at europe. Think Czechsolovakia, Hungary, North Italy. Remember those interwar Swiss Alp races? The whole point of them is that they thoroughly tested an airplane's mettle for militaries, rather than the popular pole racing which is at 100 feet. And lots of planes failed, the 109 Udet flew in that race broke its engine over those mountains.
At several airfields you do literally have to orbit in a climb before you go anywhere. It burns fuel. You'll find yank fighter group reports in north Italy in 45 talking about having to climb near the airfield before going anywhere, I know that without even looking it up, test me on it. The relevance is that it burns fuel. You have to do this in the Balkans, you have to do this around southern Romania, you have to do this in Bavaria, in northwest Czechsolovakia, in southern Poland, in Hungary, etc.
And remember we're talking about planes which have much closer performance to a modern civvy job than they do a modern jet fighter. They don't exactly climb spritely, takes like half an hour for combat height from brakes off as opposed to 2-3min.
Do you know why combat on the Eastern Front was at such low alt? Aside from the guts of the battlefronts being across all the swamps and fields, it was the proximity of the airfields to each other. They just plain didn't have the space to climb very high before meeting the enemy, and staging over the airfield for climb and formation meant your troops were being attacked with IL2s while you were scared of russian fighters, and vice versa. It went with the territory, and was a similar air war in some respects to North Africa.
And you're using this as an example of Messers not having to worry about altitude in assessing general service ranges. Right. Only the USSR wasn't the sovereign territory they should ultimately defend.