There are various letters which are interchangable and "Sch" is a sound that can be "C" or "S" which cut the name down to another possible spelling like "Sanskowski" and since the "w" can be a "v" the name can be spelled "Sanskovski" and so it goes.
To pronouce a word in German depends upon the German's dialect.
Also, I have no idea how educated Grossmann was or even if he, himself, was from Berlin or elsewhere. [Note: Missed this, article said he was from Neurueppin but I'm not familar with this place].
The only thing we seem to be able to say, the Berlin police thought it was a name which linked FS who's family was told they believed Grossmann had murdered her.
Also, if the German court had seen enough information which indicated AA was FS then they would have been able to rule that AA couldn't have been GD Anastasia because she was FS, BUT, they did not. And they certainly had a lot of information after ALL those years.
AGRBear