The default calendar for Numista is AD. Many items, and many countries, only use AD dates (Julian, and Gregorian). Looking at those pages most users will understand the numbers that look like dates are AD.
But there was a recent discussion of this page: N#43539
The page says the calendar is Vikram Samvat, but it doesn't describe the calendar and doesn't have a link to a definition of the calendar. Someone who doesn't know the relationship between VS and AD won't know which date is which.
The situation would be improved if
Years 1938-1943 (1881-1886)
Calendar Vikram Samvat
was changed to
Calendar Vikram Samvat (VS)
Years 1938-1943 VS (1881-1886 AD)
and the “Date” in the header of the mintage line table was “Date: VS(AD)” to explain the mintage line dates.