Maybe... you haven't been exactly clear about what you're reporting, then?

"Count it out yourself."

Count what out? I can click through every single month, and find every single Earth day represented (including 2/29). What dates are impossible for you to select? How is it at all uncertain which date is being selected?

To clarify, what I am interpreting your report to be, is that, for example, the 8th Sun of the First Umbral Moon should be the equivalent of February 8th, but according to your perceived error, some miscount, it is represented as February 7th, thus causing all future dates of that month to not "line up" (Feb. 10 would fall on the 9th Sun, etc, futher exacerbated as more "errors" accumulate).

And what we've tried explaining, is that, there are more Eorzean dates than Earth dates, so some Earth dates will be represented twice. February 7 is represented by both the 7th Sun of the First Umbral Moon, and the 8th Sun of the First Umbral Moon. Unless somehow we're not understanding the crux of your finding, nobody else sees the dates as inaccurate or otherwise in error.