I doubt that the two terms would be confused, as the term "chandler" is a french term and pronounced "shahndlair" by a french native. An Englishman would have pronounced it "shandler", so I do not think that the term would be confused with "Kohmishonur".
But these are the types of things that cannot be overlooked. Many of the recording monks in these parishes were French, particularly in London. So if one's surname was "Saint John", pronounced "SinJin", I could understand how it would be recorded as "Sension."
What I cannot understand is why it would continue for three generations in New England.