Flying Crane
Sr. Grandmaster
I believe it has to do with the written translation from the kanji into the Roman alphabet. I recall hearing that due to some translation issue it is supposed to be spelled with an m, but is pronounced with an n, which causes people to want to spell it with an n.Sort of. When the different styles got 'translated' to English, it was fifty/fifty whether kenpo or kempo would be chosen, from how I understand it, but once one was chosen it stuck. And would continue down that way through a lineage. Because of that it can become an important way to distinguish when talking about different styles.
Pretty sure that's how the change between kenpo/kempo worked, it's been a while since I've had reason to think about it. Anyone with a different understanding, feel free to correct me.
Honestly, I think it does not matter.