I’ve just re-read your original post – and there is no question in my mind that on a bumpy road you are always going to get a much rougher ride with girders than with telescopic forks. There may be nothing wrong with your forks. A rigid rear end doesn’t do much for comfort either of course.
Poor fork spindle adjustment is unlikely to result in a rougher ride but it will adversely affect the handling and roadholding. Regular checking is essential, as is lubrication or your spindles will wear rapidly. There is plenty of source material on how to maintain your girder forks in period publications.