Takes up to a decade for a body to decompose but lets just say for the sake of argument, God intervened in this case and preserved her. But:
"In 2021, 5.0 million children under 5 years of age died. Globally, infectious diseases, including pneumonia, diarrhoea and malaria, remain a leading cause of under-five deaths, along with preterm birth and intrapartum-related complications."
and
"more than 10 million people died of cancer worldwide each year"
What would be the purpose of a god preserving a nun, and relying on mans free will to dig her up rather than addressing real issues?