You are quite correct that the B+W filters 22 and 23 are simple optical low pass filters. What you seem to be missing is that the Wratten 12 (Minus Blue) has both a low pass element where the straight line straddles across 500 nanometers PLUS a highly complex curve that delivers a variable response across the 300 - 343 nanometer spectrum (which is outside of what the typical human eye can respond to: i.e. wavelengths from about 390 to 700 nanometers) but one that film does respond to. You can view the curve here: http://motion.kodak.com/motion/uploa...ters/W2-12.pdf
However, as stated earlier, the best way to assess the effect of filters is by doing practical tests which, I am sure you will find, demonstrates that the Wratten 12 is indeed a very special filter in terms of the relationship between effect and filter factor.