While lenses were on average softer in the era of silent movies than they are now, they are not soft enough to produce the effects you want, at least not the average ones. Anastigmats were readily available by the 20s and many if not virtually all cinematographers were using those designs if not "better". Look on Flickr for any picture shot with a Cooke Triplet or a Tessar - I can't say if these were typical for cinema lenses in that day, but the designs were decades old by the 20s and in mass production.

As for focal length, bear in mind that even "35mm" cinema negatives are not always the same size as 35mm still negatives. In your link, David Mullen says these were frequently shot on 4-perf. This is half of an 8-perf 24x36mm negative and half of a modern "full frame" sensor. If what he says about focal lengths is true, you'll need to match the perspective/focal length of those lenses on 4-perf instead of full frame.

For diffusion, many movies were shot using nets. I don't know the evolution exactly, but this started by stretching stockings over lenses to create a pattern that diffracted and softened the image. Stockings are not "perfect" distracting materials, and in addition to the softening of the image and the small puffy "glow" around highlights, will usually create halations and lower the contrast of the image. I cannot find any information confirming it, but Pandora's Box sure looks like a net to me.

Modern brown through white nets will give a similar effect to stockings, although more controllable, and not as strong. Black nets will resist halating and lowering contrast.