In reference to what I posted here my advise is that you read again the original Löfgren works/solutions on tonearm/cartridge alignment. It's useless to follow the analysis with you till you read that original white papers where you could find out that the effective lenght does not change because is one of the fixed numbers/value in the equations solution ( we can change it if we want it but this is not the main subject. ) As I said what Löfgren equations solutions ( and Baerwald/Bauer/Pisha/Stevenson/et. ) gives are: offset angle, overhang, pivot to spindle distance ( by diference. ) and null points not effective lenght.
We can manipulate those equations to achieve a tonearm effective lenght but that again is not the subject on what I'm refering to. I'm talking of the Löfgren original work.
Enough for now.
Regards and enjoy the music,
R.