Getting close means adjust by screws(screws on balance wheel) can now be fruitful.
You were right to think both hairsprings have same springness, same "CGS", different length however.
I agree with transporter, positional errors are generally due to wear on, jewels also pivots and excess endshake lets different part of pivot come to contact with the jewel hole also in cases there are endstones, pivot end comes to picture as well.
I hope this helps.
IPA used in manufactering is 95 % ( 5 % disapears when the cap is removed). the stuff you get at the phamacy is about 75% the rest is WATER. if it not sterile, it may leave a stain. it was also used to steralize breathing masks in aircraft. what a great day it will be when someone invents a glue, for the vintage watcher that WITHSTAND I.P.A.. vin