What is the "correct" VTA for the Lyra Atlas?

I am brand new to a rekindled interest in Vinyl, after 30 years of CD exclusively. In order to save money I have jumped in at the deep end, to try and avoid upgraditis! I have a clear audio Master Solution AMG Wood with CMB, with Kuzma 4 Point arm and both the Lyra Delos and Atlas cartridges.
Initial setup of the Atlas, revealed remarkable sound, could not tell the difference in frequency span between SACD and Vinyl of the same recording, the vinyl just had a more "musical" sound, I suspect fuller midrange, and less hash in the top. In my quest for perfection, I got a Dino-lite microscope and measured the VTA, which was 22 degrees, now the recommendation is for 20 degrees, so i lowered the arm as low as it would go, and managed to get it down to 21 degrees (reset the tracking force), and the top end disappeared, cymbals were not there, started sounding wooly and sweet, much like the Airtight MC-1. So went back to 22 degrees, and I prefer that sound. Now SRA is impossible to measure, because I find it depends a great deal on where I choose to draw the lines, and I suspect on the Atlas, seeing as though 3years, the diamond will be mounted correctly. Lyra are quite specific about the tracking force 1.72g and the VTA 20 degrees, and I do believe they know what they are talking about!! What should I do? My arm has this ability to fine tune VTA on the fly, isn't this ridiculous? I have seen how far the arm has to be lowered to make a 1 degree difference in VTA some 5mm, and since cutting heads apparently vary from 10 to 30 degrees, what possible difference can a changed in arm height of 0.1mm make?
Secondly, when I set tracking force using a digital meter, as I lower the cartridge, the meter starts reading -ve, as the magnet attracts the measuring plate. I suspect the force I have set is too low by a factor of the magnetic attraction?? Is this a valid concern? My work around is to lower the cartridge and then re zero the meter with the stylus just above the measuring plate.
I suppose you can see, I am out of my depth here, and would welcome, any advice.