Clearly, most of Germany's war aims failed in WWII, but were there some residual successes?
I can think of at least one contender.
Although Nazi Germany did not defeat Communism, (indeed in defeat it introduced Communism to new areas of Eastern Europe), it did oblige the USSR to disband the Comintern early in 1943, apparently in order for Moscow to reassure its allies.
Did the disbandment of the Comintern really lift some of the threat to the non-Communist world, or was it more a matter of appearance than substance?
If substance, I would suggest that the disbandment of the Comintern represents a successful German achievement that had long term ramifications.