So, Siliguri is also in Darjeeling district. But, none from Siliguri would say he/she is from Darjeeling. And the OP did not say Darjeeling district. Anyway, it's a trifling matter to argue.

In the main context, Ganga Bardan also did not write this song himself, most probably. This song he possibly collected from Sankhuwasabha or Bhojpur or Dhankuta or any other place in the eastern hill. IDK what is the fuss here.