As has been mentioned, reforms to calendars have been done before. Even most Indian Panckang makers discarded Saliva Sidhant in favour of modern astronomical formulas for calculating the Panchangas. The Panchangas, lantris and Tith Patrikas published in Punjab have all switched over to the modern methods. The sankrantis calculated on the basis of Surya Sidhanta and modern methods, may in some cases differ by 1 day. The beginning of the Khalsa Samvat be fixed in relation to the Common Era.
Many dates are worth considering.
Vaisakhi may be fixed on April 1. This date is close to the spring equinox. Sankrantis were very close to date 1 of the Julian calendar m 1699, the year of the creation of the Khalsa. From 1469 to September 1752, sankrantis occurred close to date 1st of each month of the Julian calendar. With the change to Gregorian calendar in 1752, sankrantis moved ahead by 11 days.