Just spent a morning wrestling with one of these headshells. I don't know what the material is that you screw the cart screws into (plaster?!) but it looks pretty rough to me and leaves very little adjustment so only spacers will do the job. SME are far more flexible.
That is until I've just come across a headshell where you actually screw into nuts located just below the Thorens headshell cover. This allows much more lateral adjustment although there is still virtually no clearance still for the tops of the screws coming through.
In future I will convert to screwing into nuts.