Mdd, I’m not sure how the source makes a difference. A member of a community which keeps this minhag is compelled to keep it either way (it’s not a minhag b’taos), and if this is not your minhag, you don’t need to keep it, since it’s not halachah p’sukah. The source of the minhag would seem to be academic.
Even if it weren’t, it could still be a completely honest error.