I am very aware of “von” vs. “van”; they simply mean “of” and really don’t count in the name.
Does not seem like the kind of string of syllables I’d expect from Germanic-only names.
Van Rensselaer - yes, I’m very aware of his name as a fan of the RevWar, and yes it is softer; a remnant of New Amsterdam and surroundings. I guess indeed they do have some softer syllables.
More examples: Van Cortland ( a once great Park and area in upper Manhattan ), Van Dijik ( which in NYC became Van Dyke as in an expressway ), and Van Vleit ( middle name of an idiot NYC mayor in the '60s ); all of which are "soft" sounding names.
But now the "named" perp isn't the "perp", so this is all now really off topic.