Dear Omprakashji, Namaskar,
There is no confusion in the matter.The definition of employee in Gratuity Act was amended in 2009 and teachers were brought within it's ambit. The amendment was given retrospective effect and made applicable from 1997.
Therefore all judgments prior to 2009 are irrelevant now and teachers right from 1997 are entitled for gratuity.
Further there is case law to the effect that non payment of gratuity is contineous cause of action and limitation would not be