One thing to note is that 'White' is an extremely broad category. There were German-backed Whites who were doing quite well, this is true, but the most meaningful interventions were by the Allies in favour of their Whites - which makes sense! The Germans had their treaty with the Bolsheviks, they had the lands they wanted and supplies they needed, at least on paper, and regime change would be very risky. This is especially the case when one considers that most of the White leadership were military men and Russian nationalists who opposed Brest-Litovsk and supported re-entering the war to fulfil Russia's obligations to her allies. Furthermore, while one shouldn't demean the Russian Civil War, the fact is that the Reds always had certain key advantages that are unlikely to change.
Firstly, they had a central position - this will remain the case, even if the German Whites are able to better threaten Petrograd the Russians will still be able to reinforce the city and cut off the small White army there, which would find it difficult to support itself.
Secondly, the plain fact of the matter is that the Whites were hated by the general population - that wasn't inevitable, they started out dominated by social democrats, SRs and other progressives but as the war went on the military commanders in the alliance naturally dominated, helped by the fact that foreign backers generally preferred them to socialists just a few shades lighter than the Communists.
Given that Germany's leadership was more right-wing at this point than that of France or Russia, it's unlikely that they differ in this respect - the Russian Communists are already suitable if unhappy neighbours, and if their existence is a sufficient eyesore that yet another war is considered worth the expense the Germans are hardly going to wage war on behalf of the SRs - who are, let me repeat, avowed defencists opposed to German aggrandisement.