lewm
you are correct in your assessment of the positioning of the adjustment screws. it is not a perfect adjustment, but it is better than nothing, which is what most arms have, nothing.
i have mounted the breuer directly on the raven via an armboard, on the back of the table now. i have installed 3 thumbscrews in the armboard where it meets the plinth in order to get some azimuth adjustment. i mounted a van den hul colibri on the breuer and am having a heck of a time getting the azimuth good. i think i need another armpod!
as far as your second statement, i really don't know why isolation is a better sound, removing resonance was an educated guess. something changed for the better, whatever it is.