We have not come across one calendar expert that would suggest any issues of the sort with the Gregorian calendar. The conversion to Gregorian to Julian lost 10 days, but that was the point of the conversion. The days of the week were consistent and were not interrupted. Calendar experts have high agreement/confidence and little contention with the Gregorian year count. The years are anchored to known celestial events and year counts for various kings and related ancient historical documentations.