
Yes, but there is probably no way to fix that as it is not possible to manually set the okurigana at present.
I'm adding it to the list
[@moderator] Sentences with the wrong reading for kanji

And it's beteer to be chaged to:
ひと月に一度
or
月に一度

Better as in "This is a way to avoid a wrong okurigana", or as in "This is how a native would write it anyway.?

Both.
We write and say:
ひと月に一度, ひと月に一回, 月に一度, 月に一回, 一ヶ月に一度,
一ヶ月に一回, 毎月一度, 毎月一回
And I think that 一月 is not wrong also, but when we saw 一月, we imagine January first of all.
ٹیگز
سارے ٹیگ ݙیکھوتندیراں
جملہ عبارت
لائسنس: CC BY 2.0 FRلوگو
We cannot determine yet whether this sentence was initially derived from translation or not.
نامعلوم ممبر ولوں لنک تھیا, تریخ نامعلوم
نامعلوم ممبر ولوں لنک تھیا, تریخ نامعلوم
نامعلوم ممبر شامل کیتا, تریخ نامعلوم
xtofu80 ولوں لنک تھیا, June 12, 2010
zipangu ولوں لنک تھیا, June 13, 2010
blay_paul کنوں ایڈٹ تھیا, June 13, 2010