The optical alignment is applied to wrong characters and isn't applied to characters that suppose to in Japanese.
e.g. a rule for フ affects both フ and ブ. and a rule for ブ doesn't affect ブ.
see the attached file.
ブ is the sonant form of フ.
Most characters in Japanese have its sonant form and the optical alignment seems to affects all of them.
optical-alignment.afpub