Festivals where you are
A festival is not a date. It is an instant in the Moon's motion, caught against the sunrise of the place you are standing in — so the same festival falls on a different day in San Jose than in Chennai, and both are right. This is which ones, and by how much.
Where you are
Asia/Kolkata · UTC+5:30
Where the family is
Asia/Kolkata · UTC+5:30
Name both places and a year. The page then runs the same Tamil Nadu calendar twice — once at each place — and lists only the days the two disagree about.