I don't know anything about cummulative distribution functions ( 4.1: Probability Density Functions (PDFs) and Cumulative Distribution Functions (CDFs) for Continuous Random Variables - Statistics LibreTexts ).
However, it seems that in your case, when chiSquare is too much higher than your modulus, it yields 0.
Do you have a link to a page that describes why this is an appropriate test for your problem? How are we supposed to interpret the result? What would you consider to be a "good" value?
Note that stringLengthHash will never use more than about 20 of the 65000+ bins. firstCharacterHash will only use 127 (at most). additiveChecksumHash will hardly ever use more than 1000. remainderHash is pretty much identical to additiveChecksumHash. So the only one with any chance of using the entire range is multiplicativeHash, which is also the only one that doesn't yield 0.
